/* Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700;800&display=swap');

/* ============================================================
   CSS VARIABLES — Blue/White Professional Theme
   ============================================================ */
:root {
  --font-heading: 'Nunito', system-ui, -apple-system, sans-serif;
  --font-body:    'Nunito', system-ui, -apple-system, sans-serif;

  --transition-fast:   0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-slow:   0.4s ease;

  --radius-sm:   8px;
  --radius-md:   12px;
  --radius-lg:   18px;
  --radius-full: 9999px;

  /* Blue-White palette (hocmai-inspired) */
  --color-primary:       #1565C0;
  --color-primary-rgb:   21, 101, 192;
  --color-primary-hover: #0D47A1;
  --color-secondary:     #0EA5E9;
  --color-success:       #10B981;
  --color-warning:       #F59E0B;
  --color-danger:        #EF4444;

  /* Surfaces */
  --bg-app:           #F1F5F9;
  --bg-surface:       rgba(255,255,255,0.96);
  --bg-surface-solid: #FFFFFF;
  --bg-surface-hover: #F8FAFC;
  --border-color:     #E2E8F0;
  --border-color-focus: #2563EB;

  /* Text */
  --text-main:    #1E293B;
  --text-muted:   #64748B;
  --text-inverse: #FFFFFF;

  /* Shadows */
  --shadow-sm:    0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md:    0 4px 14px rgba(0,0,0,0.08), 0 2px 6px rgba(0,0,0,0.04);
  --shadow-lg:    0 10px 32px rgba(0,0,0,0.1), 0 4px 10px rgba(0,0,0,0.05);
  --shadow-chunky: var(--shadow-md); /* compatibility alias */
  --shadow-btn:   0 2px 8px rgba(21,101,192,0.28);
  --glass-blur:   12px;
}

[data-theme="dark"] {
  --bg-app:           #0F172A;
  --bg-surface:       rgba(30,41,59,0.96);
  --bg-surface-solid: #1E293B;
  --bg-surface-hover: #263447;
  --border-color:     rgba(148,163,184,0.14);
  --border-color-focus: #60A5FA;

  --color-primary:       #60A5FA;
  --color-primary-hover: #93C5FD;
  --color-secondary:     #38BDF8;

  --text-main:    #F1F5F9;
  --text-muted:   #94A3B8;
  --text-inverse: #0F172A;

  --shadow-sm:  0 1px 3px rgba(0,0,0,0.3);
  --shadow-md:  0 4px 14px rgba(0,0,0,0.4);
  --shadow-lg:  0 10px 32px rgba(0,0,0,0.55);
  --shadow-btn: 0 2px 8px rgba(96,165,250,0.28);
}

/* ============================================================
   RESET
   ============================================================ */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html { overflow-x: hidden; } /* fix iOS Safari: không đặt overflow-x:hidden trên body */

body {
  font-family: var(--font-body);
  background-color: var(--bg-app);
  color: var(--text-main);
  min-height: 100vh;
  /* overflow-x: hidden đặt trên html thay vì body — tránh bug iOS Safari làm fixed elements không click được */
  line-height: 1.55;
  transition: background-color 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1,h2,h3,h4,h5,h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
}

a { color: inherit; text-decoration: none; }

button, input, textarea, select {
  font-family: inherit;
  outline: none;
}

img { max-width: 100%; height: auto; display: block; }

/* Hide decorative kid elements */
.ambient-glow, .ambient-glow-2, .kid-shape { display: none !important; }

/* ============================================================
   KEYFRAMES
   ============================================================ */
@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes bounceIn {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes slideUpModal {
  from { opacity: 0; transform: translateY(20px) scale(0.97); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes float {
  0%,100% { transform: translateY(0); }
  50%      { transform: translateY(-8px); }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ============================================================
   NAVBAR
   ============================================================ */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-surface-solid);
  border-bottom: 3px solid var(--color-primary);
  padding: 0 5%;
  height: 64px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 2px 12px rgba(21,101,192,0.1);
  transition: background 0.3s ease;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.45rem;
  font-weight: 800;
  color: var(--color-primary);
  cursor: pointer;
  transition: opacity var(--transition-fast);
  user-select: none;
}

.nav-brand:hover { opacity: 0.82; }

.nav-brand i {
  color: var(--color-secondary);
  font-size: 1.35rem;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  -webkit-tap-highlight-color: transparent;
  min-height: 40px;
  line-height: 1;
}

.btn-primary {
  background: var(--color-primary);
  color: #FFFFFF;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-btn);
}

.btn-primary:hover {
  background: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
  box-shadow: 0 4px 14px rgba(21,101,192,0.38);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: var(--shadow-btn);
}

.btn-secondary {
  background: var(--bg-surface-solid);
  color: var(--text-main);
  border-color: var(--border-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background: var(--bg-surface-hover);
  border-color: #CBD5E1;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary:active {
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: var(--radius-md);
}

/* ============================================================
   MAIN CONTAINER
   ============================================================ */
.main-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.75rem 1.5rem;
  min-height: calc(100vh - 64px);
}

/* SPA sections */
.view-section {
  display: none;
  animation: slideUp var(--transition-normal) forwards;
}
.view-section.active { display: block; }

/* ============================================================
   HERO BANNER SLIDER
   ============================================================ */
.hero-slider {
  position: relative;
  height: 360px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: 2rem;
  background: var(--bg-surface-solid);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.slider-slides { position: relative; width: 100%; height: 100%; }

.slider-slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 0.8s ease;
  z-index: 0;
}
.slider-slide.active { opacity: 1; z-index: 1; }

.slider-slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.slider-empty {
  width: 100%; height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #EFF6FF 0%, #DBEAFE 100%);
  color: var(--text-muted);
  font-weight: 600;
  gap: 1rem;
  text-align: center;
  padding: 2rem;
}
[data-theme="dark"] .slider-empty {
  background: linear-gradient(135deg, #1E293B, #0F172A);
}

.slider-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 40px; height: 40px;
  background: rgba(255,255,255,0.92);
  border: 1px solid rgba(0,0,0,0.1);
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.88rem;
  color: var(--text-main);
  opacity: 0;
  transition: opacity 0.2s, background 0.2s, color 0.2s;
  z-index: 5;
  box-shadow: 0 2px 10px rgba(0,0,0,0.15);
}
.hero-slider:hover .slider-btn { opacity: 1; }
.slider-prev-btn { left: 1rem; }
.slider-next-btn { right: 1rem; }
.slider-btn:hover { background: var(--color-primary); color: #FFFFFF; }

.slider-dots {
  position: absolute;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 0.5rem;
  z-index: 5;
}
.slider-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: rgba(255,255,255,0.5);
  border: 1.5px solid rgba(255,255,255,0.85);
  cursor: pointer;
  transition: all 0.22s;
}
.slider-dot.active { background: #FFFFFF; transform: scale(1.35); }

/* Banner admin row */
.banner-img-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  margin-bottom: 0.5rem;
  transition: border-color var(--transition-fast);
}
.banner-img-row:hover { border-color: var(--color-primary); }

.banner-edit-overlay-container {
  position: absolute;
  top: 1rem; right: 1rem;
  z-index: 10;
  display: none;
}
.banner-edit-overlay-btn {
  width: 40px; height: 40px;
  border-radius: 50%;
  background: rgba(255,255,255,0.92);
  border: 1px solid rgba(0,0,0,0.1);
  color: var(--text-main);
  font-size: 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-fast);
}
.banner-edit-overlay-btn:hover {
  background: var(--color-primary);
  color: #FFFFFF;
  transform: scale(1.08);
}

/* ============================================================
   BANNER CROP MODAL
   ============================================================ */
.banner-crop-modal-box {
  max-width: 820px;
  width: 95vw;
}

.banner-crop-wrap {
  width: 100%;
  background: #111;
  border-radius: var(--radius-md);
  overflow: hidden;
  max-height: 420px;
}
.banner-crop-wrap img { display: block; max-width: 100%; }

/* Override Cropper.js crop-box line colors to match theme */
.cropper-view-box,
.cropper-face {
  border-radius: 0;
}
.cropper-dashed { border-color: rgba(255,255,255,0.4); }
.cropper-line { background-color: var(--color-primary); }
.cropper-point { background-color: var(--color-primary); }

.banner-crop-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.9rem;
  flex-wrap: wrap;
}

.banner-crop-ctrl-btn {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 0.75rem;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-surface-solid);
  color: var(--text-main);
  font-size: 0.88rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-body);
}
.banner-crop-ctrl-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--bg-surface-hover);
}

/* Upload progress overlay inside crop modal */
.banner-crop-uploading-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.6);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  z-index: 10;
  border-radius: var(--radius-md);
  color: #fff;
  font-weight: 700;
  font-family: var(--font-body);
}

/* ============================================================
   SEARCH & FILTERS
   ============================================================ */
.search-filter-bar {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  margin-bottom: 1.5rem;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: center;
  box-shadow: var(--shadow-sm);
}

.search-box {
  position: relative;
  flex: 1;
  min-width: 200px;
}
.search-box i {
  position: absolute;
  left: 0.9rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 0.95rem;
  pointer-events: none;
}
.search-input {
  width: 100%;
  padding: 0.65rem 0.875rem 0.65rem 2.6rem;
  background: var(--bg-app);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.9rem;
  font-weight: 600;
  transition: all var(--transition-fast);
}
.search-input:focus {
  border-color: var(--color-primary);
  background: var(--bg-surface-solid);
  box-shadow: 0 0 0 3px rgba(21,101,192,0.12);
}
.search-input::-webkit-search-cancel-button,
.search-input::-webkit-search-decoration,
.search-input::-webkit-search-results-button,
.search-input::-webkit-search-results-decoration { display: none; }

.filter-group { display: flex; gap: 0.6rem; flex-wrap: wrap; }

.filter-select {
  padding: 0.65rem 2.1rem 0.65rem 0.85rem;
  background: var(--bg-app);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-weight: 600;
  cursor: pointer;
  font-size: 0.875rem;
  transition: all var(--transition-fast);
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2364748B'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.55rem center;
  background-size: 1rem;
}
[data-theme="dark"] .filter-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2394A3B8'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
}
.filter-select:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(21,101,192,0.12);
}

/* ============================================================
   CATEGORY BADGES
   ============================================================ */
.category-badges {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.75rem;
  overflow-x: auto;
  padding-bottom: 4px;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.category-badges::-webkit-scrollbar { display: none; }

.category-badge {
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-full);
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}
.category-badge.active,
.category-badge:hover {
  background: var(--color-primary);
  color: #FFFFFF;
  border-color: var(--color-primary);
}
.category-badge:active { transform: scale(0.96); }

/* ============================================================
   SECTION HEADER
   ============================================================ */
.section-header {
  margin-bottom: 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-left: 1rem;
  border-left: 4px solid var(--color-primary);
}
.section-header h2 { font-size: 1.55rem; color: var(--text-main); }

/* ============================================================
   COURSE GRID & CARDS
   ============================================================ */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}

.course-card {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
}
.course-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: #CBD5E1;
}

.course-thumbnail-wrapper {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  overflow: hidden;
  background: linear-gradient(135deg, #DBEAFE, #EFF6FF);
}
[data-theme="dark"] .course-thumbnail-wrapper {
  background: linear-gradient(135deg, #1e3a5f, #1e293b);
}
.course-thumbnail {
  position: absolute;
  inset: 0;
  width: 100%; height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}
.course-card:hover .course-thumbnail { transform: scale(1.04); }

.course-tags {
  position: absolute;
  top: 0.75rem; left: 0.75rem;
  display: flex;
  gap: 0.4rem;
  z-index: 2;
}
.course-tag {
  padding: 0.25rem 0.7rem;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 700;
  color: #FFFFFF;
}
.tag-category { background: rgba(21,101,192,0.82); backdrop-filter: blur(4px); }
.tag-level    { background: rgba(14,165,233,0.82); backdrop-filter: blur(4px); }

.free-badge-img {
  position: absolute; top: 4px; right: 4px; z-index: 5;
  width: 84px; height: 84px;
  pointer-events: none; user-select: none;
  filter: drop-shadow(0 4px 10px rgba(0,0,0,0.35));
}

.course-body {
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  flex: 1;
}
.course-card-title {
  font-size: 1.08rem;
  line-height: 1.4;
  margin-bottom: 0.55rem;
  color: var(--text-main);
  font-weight: 700;
  transition: color var(--transition-fast);
}
.course-card:hover .course-card-title { color: var(--color-primary); }

.course-card-desc { display: none; }

.course-meta {
  border-top: 1px solid var(--border-color);
  padding-top: 0.875rem;
  display: flex;
  justify-content: space-between;
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 1rem;
  margin-top: auto;
}
.course-meta-item { display: flex; align-items: center; gap: 0.3rem; }
.course-meta-item i { color: var(--color-primary); }

/* Progress */
.course-progress-wrapper { display: flex; flex-direction: column; gap: 0.35rem; }
.progress-info { display: flex; justify-content: space-between; font-size: 0.8rem; font-weight: 700; }
.progress-label { color: var(--text-muted); }
.progress-percent { color: var(--color-primary); }
.progress-bar-bg {
  width: 100%; height: 6px;
  background: var(--bg-app);
  border-radius: var(--radius-full);
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-full);
  width: 0%;
  transition: width var(--transition-slow);
}

/* Empty state */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  background: var(--bg-surface-solid);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}
.empty-state i {
  font-size: 3.75rem;
  color: var(--color-primary);
  margin-bottom: 1rem;
  opacity: 0.55;
  display: block;
  animation: float 4s ease-in-out infinite;
}
.empty-state h3 { font-size: 1.45rem; margin-bottom: 0.5rem; }
.empty-state p { color: var(--text-muted); margin-bottom: 1.5rem; font-weight: 500; }

/* ============================================================
   COURSE PLAYER VIEW
   ============================================================ */
.player-layout {
  display: grid;
  grid-template-columns: 1fr 350px;
  gap: 1.75rem;
  align-items: start;
}

.player-main {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  min-width: 0;
}

.video-player-container {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #000;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}
.video-player-container video {
  position: absolute; inset: 0; width: 100%; height: 100%;
}
.iframe-video {
  position: absolute; inset: 0; width: 100%; height: 100%; border: none;
}
.video-placeholder {
  position: absolute; inset: 0;
  display: flex; flex-direction: column;
  justify-content: center; align-items: center;
  color: #FFFFFF;
  background: linear-gradient(135deg, #1E293B, #0F172A);
  text-align: center; padding: 2rem;
}
.video-placeholder i {
  font-size: 4rem; color: var(--color-warning); margin-bottom: 1rem;
}

/* Player info box */
.course-player-info {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}
.player-course-breadcrumbs {
  font-size: 0.82rem; font-weight: 700;
  color: var(--color-secondary);
  margin-bottom: 0.5rem;
}
.player-lesson-title {
  font-size: 1.5rem; margin-bottom: 0.75rem; color: var(--text-main);
}
.player-lesson-desc {
  color: var(--text-muted); font-size: 0.925rem; line-height: 1.6;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.25rem; margin-bottom: 1.25rem; font-weight: 500;
}
.lesson-control-strip {
  display: flex; justify-content: space-between;
  align-items: center; flex-wrap: wrap; gap: 1rem;
}
.completion-checkbox-wrapper {
  display: flex; align-items: center; gap: 0.6rem;
  cursor: pointer; user-select: none;
}
.completion-checkbox {
  width: 24px; height: 24px;
  border: 2px solid var(--border-color);
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition-fast);
  color: transparent;
  background: var(--bg-surface-solid);
  flex-shrink: 0;
}
.completion-checkbox-wrapper:hover .completion-checkbox { border-color: var(--color-primary); }
.completion-checkbox.checked {
  background: var(--color-success);
  border-color: var(--color-success);
  color: #FFFFFF;
}
.completion-checkbox-label { font-weight: 700; font-size: 0.9rem; }
.completion-checkbox.checked + .completion-checkbox-label { color: var(--color-success); }

/* ============================================================
   TABS
   ============================================================ */
.player-tabs {
  display: flex;
  border-bottom: 2px solid var(--border-color);
  background: var(--bg-surface-solid);
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  overflow: hidden;
}
.player-tab-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 0.9rem; font-weight: 700;
  padding: 0.875rem 1.25rem;
  cursor: pointer;
  position: relative;
  font-family: var(--font-body);
  transition: color var(--transition-fast), background var(--transition-fast);
  flex: 1;
  text-align: center;
  min-height: 48px;
}
.player-tab-btn:hover { color: var(--text-main); background: var(--bg-surface-hover); }
.player-tab-btn.active { color: var(--color-primary); }
.player-tab-btn.active::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 100%; height: 2px;
  background: var(--color-primary);
}

.tab-content { display: none; }
.tab-content.active { display: block; }

/* ============================================================
   DISCUSSION / COMMENTS
   ============================================================ */
.discussion-section { display: flex; flex-direction: column; gap: 1.25rem; padding-top: 1rem; }

.comment-form {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  display: flex; flex-direction: column; gap: 0.875rem;
  box-shadow: var(--shadow-sm);
}
.comment-input-row { display: grid; grid-template-columns: 1fr; gap: 0.75rem; }

.form-control {
  width: 100%;
  padding: 0.7rem 1rem;
  background: var(--bg-app);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  font-size: 16px; /* prevent iOS zoom */
  font-weight: 500;
  transition: all var(--transition-fast);
}
.form-control:focus {
  border-color: var(--color-primary);
  background: var(--bg-surface-solid);
  box-shadow: 0 0 0 3px rgba(21,101,192,0.1);
}
textarea.form-control { resize: vertical; min-height: 100px; }

.comment-list { display: flex; flex-direction: column; gap: 0.875rem; }

.comment-card {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  box-shadow: var(--shadow-sm);
}
.comment-header {
  display: flex; justify-content: space-between;
  align-items: center; margin-bottom: 0.625rem;
}
.comment-author-avatar {
  width: 34px; height: 34px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #FFFFFF;
  display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 0.85rem; flex-shrink: 0;
}
.comment-meta-info { display: flex; align-items: center; gap: 0.75rem; }
.comment-author { font-weight: 700; font-size: 0.9rem; color: var(--text-main); }
.comment-date { font-size: 0.77rem; font-weight: 500; color: var(--text-muted); }
.comment-body {
  font-size: 0.9rem; color: var(--text-main); font-weight: 500;
  line-height: 1.55; padding-left: 2.5rem;
}

/* ============================================================
   PLAYER SIDEBAR
   ============================================================ */
.player-sidebar {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
}
.sidebar-title {
  font-size: 1rem;
  padding: 1.1rem 1.25rem;
  display: flex; justify-content: space-between; align-items: center;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-surface-solid);
  flex-shrink: 0;
}
.sidebar-title h3 { font-size: 0.975rem; font-weight: 700; }
.lessons-count-badge {
  font-size: 0.77rem; font-weight: 700;
  background: var(--color-primary); color: #FFFFFF;
  padding: 0.2rem 0.6rem; border-radius: var(--radius-full);
}
.sidebar-progress {
  padding: 0.875rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  flex-shrink: 0;
}
.lesson-list {
  flex: 1; overflow-y: auto;
  padding: 0.75rem;
  display: flex; flex-direction: column; gap: 0;
}

/* Chapter headers */
.sidebar-chapter-header {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  background: var(--bg-app);
  border-radius: var(--radius-sm);
  margin-bottom: 0.25rem;
  cursor: pointer; user-select: none;
  font-weight: 700; font-size: 0.78rem;
  color: var(--text-muted);
  text-transform: uppercase; letter-spacing: 0.04em;
  transition: background var(--transition-fast), color var(--transition-fast);
}
.sidebar-chapter-header:hover {
  background: rgba(21,101,192,0.06);
  color: var(--color-primary);
}
.sidebar-chapter-name { flex: 1; min-width: 0; }
.sidebar-chapter-chevron {
  font-size: 0.7rem; color: var(--text-muted);
  transition: transform 0.2s ease; flex-shrink: 0;
}
.sidebar-chapter-body {
  padding-left: 0.25rem; margin-bottom: 0.5rem;
  display: flex; flex-direction: column; gap: 0.2rem;
}

.lesson-item {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.75rem 0.875rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  background: transparent;
  -webkit-tap-highlight-color: transparent;
  min-height: 44px;
}
.lesson-item:hover {
  background: rgba(21,101,192,0.05);
  border-color: rgba(21,101,192,0.15);
}
.lesson-item.active {
  background: rgba(21,101,192,0.09);
  border-color: rgba(21,101,192,0.25);
}
.lesson-item.active .lesson-item-title { color: var(--color-primary); font-weight: 700; }

.lesson-status-icon { font-size: 1rem; color: var(--text-muted); flex-shrink: 0; }
.lesson-item.completed .lesson-status-icon { color: var(--color-success); }
.lesson-item.active .lesson-status-icon { color: var(--color-primary); }

.lesson-item-body { flex: 1; display: flex; flex-direction: column; gap: 0.15rem; min-width: 0; }
.lesson-item-title {
  font-size: 0.875rem; line-height: 1.4; color: var(--text-main); font-weight: 600;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.lesson-item-meta { font-size: 0.75rem; font-weight: 600; color: var(--text-muted); }
.lesson-item.active .lesson-item-meta { color: rgba(21,101,192,0.65); }

/* ============================================================
   MODAL
   ============================================================ */
.modal-overlay {
  position: fixed; inset: 0;
  background: rgba(15,23,42,0.62);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 10000;
  display: none;
  justify-content: center;
  align-items: flex-end;
  padding: 0;
}
@media (min-width: 640px) {
  .modal-overlay { align-items: center; padding: 1.5rem; }
}
.modal-overlay.active { display: flex; }

.modal-box {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  width: 100%; max-width: 100%;
  max-height: 92vh; overflow-y: auto;
  box-shadow: var(--shadow-lg);
  animation: slideUpModal 0.28s ease forwards;
}
@media (min-width: 640px) {
  .modal-box {
    border-radius: var(--radius-lg);
    max-width: 680px;
    max-height: calc(100vh - 3rem);
  }
}

.modal-header {
  padding: 1.1rem 1.5rem;
  border-bottom: 1px solid rgba(255,255,255,0.12);
  display: flex; justify-content: space-between; align-items: center;
  background: var(--color-primary);
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  flex-shrink: 0;
}
.modal-title { font-size: 1.05rem; font-weight: 700; color: #FFFFFF; }
.modal-close-btn {
  background: rgba(255,255,255,0.14);
  border: 1px solid rgba(255,255,255,0.2);
  color: #FFFFFF; font-size: 0.95rem;
  width: 32px; height: 32px; border-radius: 50%;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}
.modal-close-btn:hover {
  background: rgba(255,255,255,0.28);
  transform: rotate(90deg);
}
.modal-body { padding: 1.5rem; }
.modal-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border-color);
  display: flex; justify-content: flex-end; gap: 0.75rem;
  background: var(--bg-surface-solid);
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

/* ============================================================
   FORMS
   ============================================================ */
.form-group { margin-bottom: 1.25rem; }
.form-label {
  display: block; font-size: 0.875rem; font-weight: 700;
  margin-bottom: 0.45rem; color: var(--text-main);
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }

/* Form list */
.form-list-container {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem; background: var(--bg-app);
}
.form-list-item-box {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.875rem; margin-bottom: 0.5rem;
  display: flex; justify-content: space-between; align-items: center;
  box-shadow: var(--shadow-sm);
}
.form-list-item-info {
  display: flex; flex-direction: column; gap: 0.2rem; min-width: 0; flex: 1;
}
.form-list-item-title { font-size: 0.9rem; font-weight: 700; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.form-list-item-url {
  font-size: 0.77rem; color: var(--text-muted);
  max-width: 350px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.form-list-item-remove {
  background: var(--color-danger); border: none; color: #FFFFFF;
  cursor: pointer; width: 30px; height: 30px;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition-fast); flex-shrink: 0; margin-left: 0.75rem;
}
.form-list-item-remove:hover { background: #DC2626; transform: scale(1.08); }
.lesson-creator-inputs {
  display: flex; flex-direction: column; gap: 1rem;
  border-top: 1px dashed var(--border-color);
  padding-top: 1rem; margin-top: 1rem;
}

/* ============================================================
   AUTH / LOGIN UI
   ============================================================ */
.user-badge-container {
  display: flex; align-items: center; gap: 0.65rem;
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  padding: 0.35rem 0.875rem;
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-sm);
}
.user-badge-info { display: flex; flex-direction: column; line-height: 1.2; }
.user-badge-name { font-weight: 700; font-size: 0.85rem; }
.user-badge-role { font-size: 0.72rem; font-weight: 600; color: var(--color-primary); }

.quick-login-container {
  margin-top: 1.25rem;
  border-top: 1px dashed var(--border-color);
  padding-top: 0.875rem;
}
.quick-login-title {
  font-size: 0.82rem; font-weight: 700;
  margin-bottom: 0.6rem; color: var(--text-muted); text-align: center;
}
.quick-login-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 0.5rem; }
.quick-login-btn {
  display: flex; flex-direction: column; align-items: center; gap: 0.2rem;
  padding: 0.6rem;
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  cursor: pointer; transition: all var(--transition-fast); text-align: center;
}
.quick-login-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-sm); }
.quick-login-btn-name { font-weight: 700; font-size: 0.82rem; }
.quick-login-btn-desc { font-size: 0.7rem; font-weight: 500; color: var(--text-muted); }

/* ============================================================
   ADMIN VIEW
   ============================================================ */
.admin-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 1.5rem;
  align-items: start;
}

.admin-sidebar {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 0.875rem;
  box-shadow: var(--shadow-sm);
}
.admin-nav { display: flex; flex-direction: column; gap: 0.2rem; }
.admin-nav-item {
  display: flex; align-items: center; gap: 0.65rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer; font-weight: 600; font-size: 0.875rem;
  transition: all var(--transition-fast); color: var(--text-muted);
  -webkit-tap-highlight-color: transparent;
}
.admin-nav-item:hover { background: rgba(21,101,192,0.06); color: var(--color-primary); }
.admin-nav-item.active {
  background: rgba(21,101,192,0.1);
  color: var(--color-primary);
  border-color: rgba(21,101,192,0.2);
  font-weight: 700;
}

.admin-content {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
  min-width: 0; overflow-x: hidden; word-break: break-word;
}
.admin-section { display: none; animation: fadeIn var(--transition-normal) forwards; }
.admin-section.active { display: block; }

.admin-lock-banner {
  text-align: center; padding: 3rem 1.5rem;
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md); background: var(--bg-app);
}
.admin-lock-banner i { font-size: 3rem; color: var(--color-primary); margin-bottom: 1rem; display: block; opacity: 0.5; }
.admin-lock-banner h4 { font-size: 1.1rem; margin-bottom: 0.5rem; }
.admin-lock-banner p { color: var(--text-muted); font-weight: 500; }

.admin-sec-title {
  margin-bottom: 1.25rem; padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-main); font-size: 1.15rem;
  display: flex; align-items: center; gap: 0.5rem;
}

.content-grade-tabs {
  display: flex; gap: 0.35rem; flex-wrap: wrap;
  margin-bottom: 1.25rem; padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}
.content-grade-tab {
  padding: 0.35rem 0.8rem;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-full);
  background: var(--bg-surface-solid);
  cursor: pointer; font-weight: 600; font-size: 0.82rem;
  font-family: var(--font-body); color: var(--text-muted);
  transition: all var(--transition-fast); white-space: nowrap;
}
.content-grade-tab:hover { border-color: var(--color-primary); color: var(--color-primary); }
.content-grade-tab.active {
  background: var(--color-primary); border-color: var(--color-primary); color: #FFFFFF;
}
.grade-tab-count { font-size: 0.75rem; opacity: 0.85; }

/* ============================================================
   AUTH MODAL TABS
   ============================================================ */
.auth-modal-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-surface-solid);
}
.auth-tab {
  flex: 1; padding: 0.875rem 1rem;
  border: none; background: transparent;
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 600;
  color: var(--text-muted); cursor: pointer;
  transition: all 0.2s;
  border-bottom: 2px solid transparent; margin-bottom: -1px;
}
.auth-tab.active { color: var(--color-primary); border-bottom-color: var(--color-primary); }
.auth-tab:hover:not(.active) { background: var(--bg-surface-hover); color: var(--text-main); }

/* ============================================================
   SOCIAL SIGN-IN BUTTONS
   ============================================================ */
.btn-google-signin,
.btn-facebook-signin {
  display: flex; align-items: center; justify-content: center; gap: 0.75rem;
  width: 100%; padding: 0.75rem 1.25rem;
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 600;
  color: var(--text-main); cursor: pointer;
  transition: all 0.2s; margin-bottom: 0.5rem; min-height: 46px;
}
.btn-google-signin:hover {
  border-color: #4285F4; box-shadow: 0 2px 10px rgba(66,133,244,0.15); background: #FAFBFF;
}
.btn-facebook-signin:hover {
  border-color: #1877F2; box-shadow: 0 2px 10px rgba(24,119,242,0.15); background: #F6F9FF;
}
.btn-google-signin:disabled,
.btn-facebook-signin:disabled { opacity: 0.7; cursor: not-allowed; transform: none; }

.auth-divider {
  display: flex; align-items: center; gap: 0.75rem;
  margin: 0.875rem 0; color: var(--text-muted);
  font-size: 0.825rem; font-weight: 600;
}
.auth-divider::before, .auth-divider::after {
  content: ''; flex: 1; height: 1px; background: var(--border-color);
}

/* ============================================================
   UPLOAD SOURCE TABS
   ============================================================ */
.upload-source-tabs { display: flex; gap: 0.4rem; margin-bottom: 0.6rem; }
.upload-source-tab {
  display: inline-flex; align-items: center; gap: 0.35rem;
  padding: 0.4rem 0.875rem;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-surface-solid);
  color: var(--text-muted); font-weight: 600; font-size: 0.82rem;
  cursor: pointer; transition: all var(--transition-fast); font-family: var(--font-body);
}
.upload-source-tab:hover { background: var(--bg-surface-hover); color: var(--text-main); }
.upload-source-tab.active { background: var(--color-primary); color: #FFFFFF; border-color: var(--color-primary); }

/* ============================================================
   FILE DROP ZONE
   ============================================================ */
.file-drop-zone {
  display: block;
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-md);
  cursor: pointer; transition: all var(--transition-fast); background: var(--bg-app);
}
.file-drop-zone input[type="file"] { display: none; }
.file-drop-zone:hover, .file-drop-zone.drag-over {
  border-color: var(--color-primary);
  background: rgba(21,101,192,0.03);
}
.file-drop-content {
  display: flex; flex-direction: column; align-items: center; gap: 0.5rem;
  padding: 1.75rem 1rem; text-align: center; pointer-events: none;
}
.file-drop-content i { font-size: 2.25rem; color: var(--color-primary); opacity: 0.6; }
.file-drop-content span { font-weight: 600; font-size: 0.9rem; color: var(--text-main); }
.file-drop-content span u { color: var(--color-primary); }
.file-drop-content small { color: var(--text-muted); font-size: 0.78rem; }

.file-preview-thumb {
  display: flex; align-items: center; gap: 1rem;
  padding: 0.75rem; border: 1px solid var(--border-color);
  border-radius: var(--radius-md); background: var(--bg-surface-solid); margin-top: 0.5rem;
}
.file-preview-thumb img {
  width: 72px; height: 54px; object-fit: cover; border-radius: var(--radius-sm);
}
.file-preview-video {
  display: flex; flex-direction: column; gap: 0.5rem;
  padding: 0.75rem; border: 1px solid var(--border-color);
  border-radius: var(--radius-md); background: var(--bg-surface-solid); margin-top: 0.5rem;
}
.file-preview-video video { width: 100%; max-height: 150px; border-radius: var(--radius-sm); background: #000; }
.video-file-info {
  display: flex; align-items: center; gap: 0.5rem;
  font-size: 0.82rem; font-weight: 600; color: var(--text-muted); overflow: hidden;
}
.video-file-info span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.remove-file-btn {
  display: inline-flex; align-items: center; gap: 0.35rem;
  padding: 0.35rem 0.75rem; background: var(--color-danger);
  color: #FFFFFF; border: none; border-radius: var(--radius-sm);
  font-weight: 600; font-size: 0.8rem; cursor: pointer;
  font-family: var(--font-body); transition: all var(--transition-fast); align-self: flex-start;
}
.remove-file-btn:hover { background: #DC2626; }

/* ============================================================
   COURSE STATS PANEL
   ============================================================ */
.course-stats-panel {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem; margin-bottom: 1.25rem; box-shadow: var(--shadow-sm);
}
.stats-panel-header {
  display: flex; align-items: center; gap: 0.5rem;
  font-weight: 700; font-size: 0.925rem; color: var(--text-main); margin-bottom: 1rem;
}
.stats-total-badge {
  margin-left: auto; font-size: 0.77rem;
  background: var(--color-primary); color: #FFFFFF;
  padding: 0.2rem 0.75rem; border-radius: var(--radius-full);
}
.stats-grades-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 0.6rem; }
.stats-grade-card {
  text-align: center; padding: 0.75rem 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); background: var(--bg-app);
  transition: all var(--transition-fast);
}
.stats-grade-card.has-content {
  border-color: rgba(21,101,192,0.2);
  background: rgba(21,101,192,0.04);
}
.stats-grade-label { font-size: 0.77rem; font-weight: 700; color: var(--text-muted); margin-bottom: 0.3rem; }
.stats-grade-card.has-content .stats-grade-label { color: var(--color-primary); }
.stats-grade-courses { font-size: 1.2rem; font-weight: 800; color: var(--text-main); line-height: 1; }
.stats-grade-courses span, .stats-grade-lessons span { font-size: 0.68rem; font-weight: 600; color: var(--text-muted); }
.stats-grade-lessons { font-size: 0.82rem; font-weight: 600; color: var(--text-muted); margin-top: 0.2rem; }

/* ============================================================
   GRADE HINT
   ============================================================ */
.grade-courses-hint {
  margin-top: 0.5rem; border-radius: var(--radius-sm);
  padding: 0.75rem 1rem; font-size: 0.82rem; font-weight: 600;
  border: 1px solid var(--border-color);
  animation: bounceIn var(--transition-fast) forwards;
}
.grade-courses-hint.hint-empty { background: rgba(16,185,129,0.06); border-color: rgba(16,185,129,0.3); color: var(--color-success); }
.grade-courses-hint.hint-has-content { background: rgba(14,165,233,0.06); border-color: rgba(14,165,233,0.3); }
.hint-header { font-weight: 700; color: var(--color-secondary); margin-bottom: 0.4rem; }
.hint-course-row { display: flex; align-items: center; gap: 0.4rem; padding: 0.25rem 0; color: var(--text-main); }
.hint-course-row i { color: var(--color-secondary); font-size: 0.77rem; flex-shrink: 0; }
.hint-course-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.hint-lesson-badge {
  background: rgba(21,101,192,0.1); color: var(--color-primary);
  border-radius: var(--radius-full); padding: 0.1rem 0.5rem;
  font-size: 0.72rem; font-weight: 700; flex-shrink: 0;
}

/* ============================================================
   MINI PLAYER
   ============================================================ */
#mini-player {
  position: fixed; bottom: 1.25rem; right: 1.25rem;
  width: 300px; background: #0D0D1A; border-radius: 12px;
  overflow: visible; box-shadow: 0 16px 48px rgba(0,0,0,0.65);
  z-index: 8000;
  animation: miniPlayerIn 0.28s cubic-bezier(0.34,1.56,0.64,1) forwards;
}
#mini-player > .mini-player-bar,
#mini-player > #mini-video-slot { border-radius: 0; }
#mini-player > #mini-video-slot { overflow: hidden; border-radius: 0 0 12px 12px; }
.mini-close-float {
  position: absolute; top: -13px; right: -13px; z-index: 9999;
  width: 30px; height: 30px; border-radius: 50%;
  background: #e53e3e; color: #fff; border: 2.5px solid #fff;
  cursor: pointer; font-size: 0.8rem;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.4);
  transition: background 0.15s, transform 0.15s;
}
.mini-close-float:hover { background: #c53030; transform: scale(1.15); }
@keyframes miniPlayerIn {
  from { opacity: 0; transform: translateY(32px) scale(0.85); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}
#mini-video-slot { width: 100%; aspect-ratio: 16/9; background: #000; display: block; overflow: hidden; }
#mini-video-slot video, #mini-video-slot iframe {
  width: 100%; height: 100%; display: block; object-fit: contain; border: none;
}
.mini-player-bar {
  display: flex; align-items: center; gap: 0.4rem;
  padding: 0.5rem 0.625rem; background: #1A1A2E;
}
.mini-player-title {
  flex: 1; font-size: 0.72rem; font-weight: 600; color: #DDE1F0;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis; font-family: var(--font-body); min-width: 0;
}
.mini-player-actions { display: flex; gap: 0.25rem; flex-shrink: 0; }
.mini-btn {
  width: 26px; height: 26px; border: none; border-radius: 6px;
  background: rgba(255,255,255,0.1); color: #FFF; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.68rem; transition: background 0.15s;
}
.mini-btn:hover { background: rgba(255,255,255,0.22); }
.mini-btn-close:hover { background: rgba(220,50,50,0.75); }

/* ============================================================
   ADD TO EXISTING CARD
   ============================================================ */
.add-to-existing-card {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  background: var(--bg-surface-solid);
  box-shadow: var(--shadow-sm); overflow: hidden;
}
.add-to-existing-header {
  display: flex; align-items: center; gap: 0.75rem;
  width: 100%; padding: 1rem 1.25rem;
  background: var(--bg-surface-solid); border: none;
  cursor: pointer; font-family: var(--font-body);
  font-weight: 700; font-size: 0.9rem; color: var(--text-main);
  text-align: left; transition: background var(--transition-fast);
}
.add-to-existing-header:hover { background: var(--bg-surface-hover); }
.add-to-existing-header i:first-child { color: var(--color-secondary); font-size: 1rem; }
.add-to-existing-header #add-existing-chevron { margin-left: auto; color: var(--text-muted); transition: transform var(--transition-fast); }
#add-to-existing-body { padding: 1.25rem; border-top: 1px solid var(--border-color); }
.existing-course-info-box {
  background: var(--bg-app); border: 1px solid var(--border-color);
  border-radius: var(--radius-md); padding: 0.875rem; margin-bottom: 1rem;
}
.existing-course-meta {
  display: flex; gap: 1.25rem; font-size: 0.82rem; font-weight: 700;
  color: var(--text-muted); margin-bottom: 0.75rem; flex-wrap: wrap;
}
.existing-course-meta i { color: var(--color-primary); }
.existing-lessons-list { display: flex; flex-direction: column; gap: 0.3rem; max-height: 175px; overflow-y: auto; }
.existing-lesson-row {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.35rem 0.5rem; background: var(--bg-surface-solid);
  border-radius: var(--radius-sm); border: 1px solid var(--border-color); font-size: 0.82rem;
}
.existing-lesson-num {
  width: 20px; height: 20px; border-radius: 50%;
  background: var(--color-primary); color: #FFFFFF;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem; font-weight: 700; flex-shrink: 0;
}
.existing-lesson-name { flex: 1; font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.existing-lesson-dur { font-size: 0.72rem; font-weight: 600; color: var(--text-muted); flex-shrink: 0; }

/* ============================================================
   COURSE TREE (Admin Content)
   ============================================================ */
.course-tree-card {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg); overflow: hidden;
  margin-bottom: 0.875rem; background: var(--bg-surface-solid);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-fast), border-color var(--transition-fast);
}
.course-tree-card:hover { border-color: rgba(21,101,192,0.3); box-shadow: var(--shadow-md); }
.course-tree-header { display: flex; align-items: center; gap: 0.875rem; padding: 0.875rem 1rem; }
.course-tree-thumb { width: 64px; height: 48px; object-fit: cover; border-radius: var(--radius-sm); border: 1px solid var(--border-color); flex-shrink: 0; }
.course-tree-info { flex: 1; min-width: 0; }
.course-tree-title {
  font-weight: 700; font-size: 0.95rem; color: var(--text-main);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis; margin-bottom: 0.25rem;
}
.course-tree-meta { display: flex; gap: 0.35rem; flex-wrap: wrap; }
.ct-tag {
  background: var(--bg-app); border: 1px solid var(--border-color);
  border-radius: var(--radius-full); padding: 0.05rem 0.5rem;
  font-size: 0.7rem; font-weight: 600; color: var(--text-muted);
}
.course-tree-actions { display: flex; gap: 0.35rem; flex-shrink: 0; align-items: center; }
.course-tree-body { border-top: 1px solid var(--border-color); padding: 0.875rem 1rem; background: var(--bg-app); }

/* Chapter blocks */
.chapter-list { display: flex; flex-direction: column; gap: 0.5rem; margin-bottom: 0.875rem; }
.chapter-block { border: 1px solid var(--border-color); border-radius: var(--radius-md); overflow: hidden; background: var(--bg-surface-solid); }
.chapter-hd {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  background: rgba(21,101,192,0.04); border-bottom: 1px solid var(--border-color);
}
.chapter-name { flex: 1; font-weight: 700; font-size: 0.82rem; color: var(--text-main); }
.chapter-count { font-size: 0.72rem; font-weight: 600; color: var(--text-muted); flex-shrink: 0; }
.chapter-lessons-list { padding: 0.25rem 0.35rem; }
.lesson-row { display: flex; align-items: center; gap: 0.5rem; padding: 0.4rem 0.5rem; border-radius: var(--radius-sm); transition: background var(--transition-fast); }
.lesson-row:hover { background: rgba(21,101,192,0.04); }
.ct-lesson-icon { color: var(--color-primary); font-size: 0.82rem; flex-shrink: 0; }
.lesson-row-body { flex: 1; min-width: 0; }
.lesson-row-title { display: block; font-weight: 600; font-size: 0.845rem; color: var(--text-main); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lesson-row-dur { font-size: 0.7rem; color: var(--text-muted); font-weight: 500; }
.lesson-row-actions { display: flex; gap: 0.25rem; flex-shrink: 0; }

.ct-btn-icon {
  width: 28px; height: 28px;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--border-color); border-radius: var(--radius-sm);
  background: var(--bg-surface-solid); cursor: pointer; color: var(--text-muted);
  transition: all var(--transition-fast); font-size: 0.72rem; flex-shrink: 0;
}
.ct-btn-icon:hover { background: var(--color-primary); border-color: var(--color-primary); color: #FFFFFF; }
.ct-btn-icon.danger:hover { background: var(--color-danger); border-color: var(--color-danger); }

.add-chapter-row { display: flex; flex-direction: column; gap: 0.5rem; }
.ct-no-content { padding: 0.75rem 0.5rem; font-size: 0.85rem; color: var(--text-muted); font-weight: 600; }

.inline-lesson-form { margin-top: 0.2rem; }
.add-chapter-inline { margin-top: 0.2rem; }
.inline-form-box {
  background: var(--bg-surface-solid);
  border: 1.5px dashed var(--color-primary);
  border-radius: var(--radius-md); padding: 0.875rem; margin-top: 0.35rem;
}
.inline-form-label { font-weight: 700; font-size: 0.845rem; color: var(--text-main); margin-bottom: 0.75rem; font-family: var(--font-body); }

/* ============================================================
   EDIT COURSE MODAL TABS
   ============================================================ */
.edit-modal-tabs { display: flex; border-bottom: 1px solid var(--border-color); background: var(--bg-surface-solid); }
.edit-modal-tab {
  flex: 1; padding: 0.875rem 1rem;
  border: none; background: transparent;
  font-family: var(--font-body); font-size: 0.875rem; font-weight: 600;
  color: var(--text-muted); cursor: pointer; transition: all 0.2s;
  display: flex; align-items: center; justify-content: center; gap: 0.4rem;
  border-bottom: 2px solid transparent; margin-bottom: -1px;
}
.edit-modal-tab.active { color: var(--color-primary); border-bottom-color: var(--color-primary); }
.edit-modal-tab:hover:not(.active) { color: var(--text-main); background: var(--bg-surface-hover); }

/* ============================================================
   USER MANAGEMENT
   ============================================================ */
.user-mgmt-row {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.75rem 0.875rem;
  border: 1px solid var(--border-color); border-radius: var(--radius-md);
  background: var(--bg-surface-solid); margin-bottom: 0.5rem;
  transition: border-color var(--transition-fast); min-width: 0;
}
.user-mgmt-row:hover { border-color: var(--color-secondary); }
.user-mgmt-avatar {
  width: 38px; height: 38px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.925rem; color: #FFFFFF; flex-shrink: 0;
}
.user-mgmt-info { flex: 1; min-width: 0; }
.user-mgmt-name { font-weight: 700; font-size: 0.9rem; color: var(--text-main); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.user-mgmt-email { font-size: 0.75rem; color: var(--text-muted); font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.role-badge { display: inline-flex; align-items: center; gap: 0.25rem; padding: 0.2rem 0.6rem; border-radius: var(--radius-full); font-size: 0.72rem; font-weight: 700; flex-shrink: 0; }
.role-badge.admin1 { background: rgba(21,101,192,0.1); color: var(--color-primary); }
.role-badge.admin2 { background: rgba(14,165,233,0.1); color: var(--color-secondary); }
.role-badge.student { background: rgba(16,185,129,0.1); color: var(--color-success); }
.user-mgmt-actions { display: flex; align-items: center; gap: 0.4rem; flex-shrink: 0; }
.user-mgmt-select {
  padding: 0.35rem 0.6rem; border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); background: var(--bg-surface-solid);
  color: var(--text-main); font-weight: 600; font-size: 0.82rem; font-family: var(--font-body); cursor: pointer;
}

.admin-content .form-control { max-width: 100%; box-sizing: border-box; }
#edit-course-chapters-tree .chapter-list { margin-bottom: 1rem; }
#edit-course-chapters-tree .course-tree-body { border-top: none; padding: 0; background: transparent; }

/* ============================================================
   SMALL BUTTON VARIANTS
   ============================================================ */
.btn-sm { padding: 0.3rem 0.65rem !important; font-size: 0.8rem !important; min-height: 32px !important; }
.btn-outline-danger { background: transparent; color: var(--color-danger); border: 1.5px solid var(--color-danger); }
.btn-outline-danger:hover { background: var(--color-danger); color: #FFFFFF; }

/* ============================================================
   VIDEO STRIP (Player)
   ============================================================ */
#lesson-video-strip {
  padding: 0.75rem;
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}
.lesson-video-strip-inner {}
.lesson-video-strip-title {
  font-weight: 700; font-size: 0.82rem; color: var(--text-main);
  margin-bottom: 0.5rem; display: flex; align-items: center; gap: 0.35rem;
}
.lesson-video-items { display: flex; flex-direction: column; gap: 0.35rem; }
.lesson-video-item {
  display: flex; align-items: center; gap: 0.65rem;
  padding: 0.55rem 0.75rem; border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-surface-solid); cursor: pointer;
  transition: all var(--transition-fast);
}
.lesson-video-item:hover { border-color: var(--color-primary); background: rgba(21,101,192,0.04); }
.lesson-video-item.active { border-color: var(--color-primary); background: rgba(21,101,192,0.08); }
.lesson-video-num {
  width: 1.35rem; height: 1.35rem; border-radius: 50%;
  background: var(--bg-app); border: 1px solid var(--border-color);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem; font-weight: 700; flex-shrink: 0;
}
.lesson-video-item.active .lesson-video-num { background: var(--color-primary); color: #FFF; border-color: var(--color-primary); }
.lesson-video-info { flex: 1; min-width: 0; }
.lesson-video-name { display: block; font-weight: 600; font-size: 0.85rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.lesson-video-dur { font-size: 0.72rem; color: var(--text-muted); font-weight: 500; }
.lesson-video-play-icon { color: var(--text-muted); font-size: 0.85rem; flex-shrink: 0; }
.lesson-video-item.active .lesson-video-play-icon { color: var(--color-primary); }

/* ============================================================
   ATTACHMENT SECTION (below player)
   ============================================================ */
#lesson-attachments-section {
  padding: 0.75rem 0.875rem;
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); box-shadow: var(--shadow-sm);
}
.lesson-attachments-header {
  display: flex; align-items: center; gap: 0.4rem;
  font-weight: 700; font-size: 0.85rem; color: var(--text-main); margin-bottom: 0.5rem;
}
.attachment-item {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.7rem 0.875rem; border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-surface-solid); text-decoration: none; color: var(--text-main);
  margin-bottom: 0.4rem; transition: all var(--transition-fast); box-shadow: var(--shadow-sm);
}
.attachment-item:hover { border-color: var(--color-secondary); transform: translateY(-1px); box-shadow: var(--shadow-md); }

/* ============================================================
   EDIT LESSON MODAL — Videos & Attachments
   ============================================================ */
.edit-video-row, .edit-attach-row {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 0.65rem; border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-surface-solid); margin-bottom: 0.35rem;
}
.edit-video-info { flex: 1; min-width: 0; }
.edit-video-name { font-weight: 600; font-size: 0.85rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.edit-video-url { font-size: 0.72rem; color: var(--text-muted); font-weight: 500; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.edit-video-dur { font-size: 0.75rem; font-weight: 600; color: var(--text-muted); flex-shrink: 0; }
.elv-add-form { background: var(--bg-app); border-radius: var(--radius-sm); padding: 0.6rem; border: 1px dashed var(--border-color); }

/* ============================================================
   TOPIC MANAGER (Admin)
   ============================================================ */
.topics-list { display: flex; flex-direction: column; gap: 0.35rem; }
.topic-row {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  background: var(--bg-surface-solid); border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); transition: border-color var(--transition-fast);
}
.topic-row:hover { border-color: var(--color-primary); }

/* ============================================================
   SCROLLBARS
   ============================================================ */
::-webkit-scrollbar { width: 5px; height: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

::selection { background: rgba(21,101,192,0.18); color: var(--text-main); }

/* ============================================================
   RESPONSIVE — MOBILE FIRST
   ============================================================ */

/* ── Small phones: ≤ 479px ── */
@media (max-width: 479px) {
  .nav-brand span { display: none; }
  .nav-brand { font-size: 1.2rem; }
  .hero-slider { height: 150px; }
  .section-header h2 { font-size: 1.15rem; }
  .course-grid { gap: 0.875rem; }
  .stats-grades-grid { grid-template-columns: repeat(3, 1fr); }
}

/* ── All phones: ≤ 639px ── */
@media (max-width: 639px) {
  /* Navbar */
  .navbar { padding: 0 1rem; height: 56px; }
  .nav-brand { font-size: 1.25rem; }
  #login-trigger-btn span { display: none; }
  .nav-actions { gap: 0.4rem; }
  .btn-icon { width: 36px; height: 36px; }
  /* Ẩn tab trong header trên mobile — dùng bottom nav thay thế */
  .main-nav-tabs { display: none; }

  /* Layout — thêm padding dưới để không bị bottom nav che */
  .main-container { padding: 1rem 0.875rem 5rem; min-height: calc(100vh - 56px); }

  /* Banner */
  .hero-slider { height: 185px; border-radius: var(--radius-md); margin-bottom: 1.25rem; }

  /* Search & Filters */
  .search-filter-bar { padding: 0.875rem; gap: 0.55rem; margin-bottom: 1.25rem; border-radius: var(--radius-md); }
  .search-box { min-width: 100%; }
  .filter-group { width: 100%; flex-wrap: nowrap; gap: 0.4rem; }
  .filter-select { flex: 1; min-width: 0; font-size: 0.82rem; padding: 0.55rem 1.6rem 0.55rem 0.65rem; }

  /* Category badges */
  .category-badges { margin-bottom: 1.25rem; gap: 0.4rem; }
  .category-badge { padding: 0.4rem 0.875rem; font-size: 0.82rem; }

  /* Course grid */
  .course-grid { grid-template-columns: 1fr; gap: 0.875rem; }

  /* Player layout */
  .player-layout { grid-template-columns: 1fr; gap: 0.875rem; }
  .player-sidebar { position: static; max-height: 400px; }
  .player-lesson-title { font-size: 1.2rem; }
  .course-player-info { padding: 1.1rem; }
  .player-tab-btn { font-size: 0.825rem; padding: 0.75rem 0.875rem; }
  .lesson-control-strip { gap: 0.75rem; }

  /* Admin layout */
  .admin-layout { grid-template-columns: 1fr; gap: 0.875rem; }
  /* Horizontal scrollable tab bar */
  .admin-sidebar {
    padding: 0.5rem;
    position: sticky; top: 56px; z-index: 50;
    border-radius: var(--radius-md);
  }
  .admin-nav {
    flex-direction: row;
    overflow-x: auto; gap: 0.3rem;
    padding-bottom: 2px; scrollbar-width: none;
  }
  .admin-nav::-webkit-scrollbar { display: none; }
  .admin-nav-item {
    flex-shrink: 0; padding: 0.5rem 0.875rem;
    font-size: 0.8rem; white-space: nowrap; border-radius: var(--radius-md);
  }
  .admin-nav-item i { font-size: 0.875rem; }
  .admin-content { padding: 1.1rem; }

  /* Forms */
  .form-row { grid-template-columns: 1fr; }
  .modal-body { padding: 1.1rem; }
  .modal-footer { padding: 0.875rem 1.1rem; }

  /* Force modal to full-width sheet on mobile */
  .modal-box { max-width: 100% !important; border-radius: var(--radius-lg) var(--radius-lg) 0 0 !important; }

  /* Stats grid on mobile */
  .stats-grades-grid { grid-template-columns: repeat(3, 1fr); }

  /* Completion label shorter on very small */
  .completion-checkbox-label { font-size: 0.85rem; }

  /* Upload tabs stack on mobile */
  .upload-source-tabs { flex-wrap: wrap; }

  /* Section header */
  .section-header h2 { font-size: 1.3rem; }
}

/* ── Tablet: 640px – 1023px ── */
@media (min-width: 640px) and (max-width: 1023px) {
  .navbar { padding: 0 2.5%; }
  .main-container { padding: 1.5rem 1.25rem; }
  .hero-slider { height: 280px; }
  .course-grid { grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
  .player-layout { grid-template-columns: 1fr; gap: 1.5rem; }
  .player-sidebar { position: static; max-height: 400px; }
  .admin-layout { grid-template-columns: 200px 1fr; gap: 1.25rem; }
}

/* ── Desktop: ≥ 1024px ── */
@media (min-width: 1024px) {
  .player-layout { grid-template-columns: 1fr 345px; }
  .admin-layout { grid-template-columns: 240px 1fr; }
}

/* ── Mini player mobile ── */
@media (max-width: 480px) {
  #mini-player { width: calc(100vw - 2rem); right: 1rem; bottom: 1rem; }
}

/* ============================================================
   USER DROPDOWN
   ============================================================ */
.user-dropdown-wrapper {
  position: relative;
}

.user-badge-container {
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast);
  border-radius: var(--radius-md);
  padding: 0.3rem 0.5rem;
}
.user-badge-container:hover { background: var(--bg-surface-hover); }

.user-dropdown-menu {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 200px;
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  z-index: 200;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s;
  overflow: hidden;
}

/* Show on hover (desktop) */
.user-dropdown-wrapper:hover .user-dropdown-menu,
.user-dropdown-wrapper.open .user-dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.user-dropdown-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.7rem 1rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}
.user-dropdown-item:hover { background: var(--bg-surface-hover); color: var(--color-primary); }
.user-dropdown-item.danger { color: var(--color-danger); }
.user-dropdown-item.danger:hover { background: rgba(239,68,68,0.06); }
.user-dropdown-item i { font-size: 0.9rem; flex-shrink: 0; opacity: 0.85; }

.user-dropdown-divider {
  height: 1px;
  background: var(--border-color);
  margin: 0.2rem 0;
}

/* ============================================================
   TEACHER INFO ON COURSE CARD
   ============================================================ */
.course-teacher {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 0.35rem;
}
.course-teacher i { font-size: 0.8rem; opacity: 0.8; }

.course-dates {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  flex-wrap: wrap;
  font-size: 0.77rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 0.35rem;
}
.course-dates i { font-size: 0.72rem; }

/* ============================================================
   FREE / LOCK BADGES — Video Strip & Sidebar
   ============================================================ */
.video-free-badge {
  display: inline-flex;
  align-items: center;
  padding: 0.15rem 0.45rem;
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: rgba(16,185,129,0.12);
  color: var(--color-success);
  border: 1px solid rgba(16,185,129,0.3);
  border-radius: var(--radius-full);
  flex-shrink: 0;
  white-space: nowrap;
}

.video-lock-icon {
  color: var(--color-warning);
  font-size: 0.75rem;
  flex-shrink: 0;
}

/* Sidebar lesson meta badges */
.sidebar-free-badge {
  display: inline-flex;
  align-items: center;
  padding: 0.1rem 0.35rem;
  font-size: 0.62rem;
  font-weight: 700;
  background: rgba(16,185,129,0.12);
  color: var(--color-success);
  border-radius: var(--radius-full);
  white-space: nowrap;
}

.sidebar-lock-icon {
  color: var(--color-warning);
  font-size: 0.65rem;
  vertical-align: middle;
}

/* ============================================================
   FREE/PAID TOGGLE BUTTON IN EDIT LESSON MODAL
   ============================================================ */
.edit-free-toggle {
  flex-shrink: 0;
  white-space: nowrap;
  border-radius: var(--radius-full) !important;
  font-size: 0.72rem !important;
  padding: 0.2rem 0.55rem !important;
  min-height: 26px !important;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.btn-free-active {
  background: rgba(16,185,129,0.1);
  color: var(--color-success);
  border: 1.5px solid rgba(16,185,129,0.4);
}
.btn-free-active:hover {
  background: rgba(239,68,68,0.08);
  color: var(--color-danger);
  border-color: rgba(239,68,68,0.3);
}

.btn-free-inactive {
  background: rgba(239,68,68,0.06);
  color: var(--color-danger);
  border: 1.5px solid rgba(239,68,68,0.2);
}
.btn-free-inactive:hover {
  background: rgba(16,185,129,0.08);
  color: var(--color-success);
  border-color: rgba(16,185,129,0.3);
}

/* ============================================================
   VIDEO LOCKED SCREEN
   ============================================================ */
.video-locked-screen {
  background: var(--bg-surface-solid) !important;
  border: 2px dashed var(--color-warning) !important;
}

/* ============================================================
   PROFILE MODAL — Purchased Course Rows
   ============================================================ */
.profile-course-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  margin-bottom: 0.5rem;
  transition: border-color var(--transition-fast);
}
.profile-course-row:hover { border-color: var(--color-primary); }

.profile-course-row img {
  width: 72px;
  height: 48px;
  object-fit: cover;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  flex-shrink: 0;
}

.profile-course-info { flex: 1; min-width: 0; }
.profile-course-title {
  font-weight: 700;
  font-size: 0.875rem;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 0.2rem;
}
.profile-course-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ============================================================
   USER MANAGEMENT — Extended Cards
   ============================================================ */
.user-mgmt-card {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  margin-bottom: 0.6rem;
  overflow: hidden;
  transition: border-color var(--transition-fast);
}
.user-mgmt-card:hover { border-color: var(--color-secondary); }

.user-mgmt-card .user-mgmt-row {
  border: none;
  border-radius: 0;
  margin-bottom: 0;
  background: transparent;
}

.user-expand-btn { flex-shrink: 0; }

.user-detail-panel {
  border-top: 1px solid var(--border-color);
  background: var(--bg-app);
}

.user-detail-inner {
  padding: 0.875rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.user-detail-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}
.user-detail-meta span {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-muted);
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  padding: 0.2rem 0.65rem;
}
.user-detail-meta i { font-size: 0.75rem; color: var(--color-primary); }

.user-purchased-section { display: flex; flex-direction: column; gap: 0.5rem; }
.user-purchased-header {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--text-main);
}
.user-purchased-count { color: var(--text-muted); font-weight: 600; font-size: 0.8rem; }

.user-purchased-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  min-height: 28px;
}

.purchased-course-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.25rem 0.5rem 0.25rem 0.65rem;
  background: rgba(21,101,192,0.08);
  color: var(--color-primary);
  border: 1px solid rgba(21,101,192,0.2);
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 700;
  max-width: 260px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.purchased-remove-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-danger);
  font-size: 0.75rem;
  padding: 0;
  line-height: 1;
  flex-shrink: 0;
  opacity: 0.7;
  transition: opacity var(--transition-fast);
}
.purchased-remove-btn:hover { opacity: 1; }

.user-add-course-row { margin-top: 0.2rem; }
.user-add-course-row .form-control { max-width: 100%; }

/* ============================================================
   CHAPTER FREE/PAID ICON BUTTONS
   ============================================================ */
.chapter-free-btn { color: var(--color-success) !important; }
.chapter-free-btn:hover { background: rgba(16,185,129,0.1) !important; }

.chapter-paid-btn { color: var(--color-warning) !important; }
.chapter-paid-btn:hover { background: rgba(245,158,11,0.1) !important; }

/* ============================================================
   USER COURSES CHECKLIST (Admin user detail panel)
   ============================================================ */
.user-courses-checklist {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  max-height: 220px;
  overflow-y: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.3rem;
  background: var(--bg-surface-solid);
  scrollbar-width: thin;
}

.course-check-item {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.4rem 0.55rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition-fast);
  user-select: none;
}
.course-check-item:hover { background: var(--bg-surface-hover); }

.course-check-item input[type="checkbox"] {
  width: 15px;
  height: 15px;
  cursor: pointer;
  flex-shrink: 0;
  accent-color: var(--color-primary);
}

.course-check-info { flex: 1; min-width: 0; }

.course-check-title {
  display: block;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-main);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.course-check-meta {
  display: block;
  font-size: 0.7rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ============================================================
   VIEW COUNT BADGES
   ============================================================ */
.sidebar-view-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  padding: 0.05rem 0.35rem;
  font-size: 0.6rem;
  font-weight: 700;
  background: rgba(21,101,192,0.08);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  white-space: nowrap;
}
.sidebar-view-badge i { font-size: 0.58rem; }

.ct-view-count {
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--color-primary);
  background: rgba(21,101,192,0.07);
  border-radius: var(--radius-full);
  padding: 0.05rem 0.4rem;
  white-space: nowrap;
  flex-shrink: 0;
}
.ct-view-count i { font-size: 0.62rem; }

/* ============================================================
   CHAPTER REORDER BUTTONS
   ============================================================ */
.ct-reorder-btn {
  color: var(--text-muted) !important;
}
.ct-reorder-btn:hover:not(:disabled) {
  background: rgba(21,101,192,0.1) !important;
  color: var(--color-primary) !important;
  border-color: rgba(21,101,192,0.25) !important;
}
.ct-reorder-btn:disabled {
  opacity: 0.25;
  cursor: not-allowed;
}

/* ============================================================
   MOBILE RESPONSIVE ADDITIONS
   ============================================================ */
@media (max-width: 639px) {
  /* Dropdown: fixed position dưới navbar để tránh bị khuất */
  .user-dropdown-menu {
    position: fixed !important;
    top: 56px !important;
    right: 0.5rem !important;
    left: auto !important;
    min-width: 220px !important;
    max-height: calc(100dvh - 70px);
    overflow-y: auto;
    z-index: 9000 !important;
    transform: translateY(-8px) !important;
    border-radius: var(--radius-md) !important;
  }
  .user-dropdown-wrapper:hover .user-dropdown-menu,
  .user-dropdown-wrapper.open .user-dropdown-menu {
    transform: translateY(0) !important;
  }
  .course-teacher { font-size: 0.78rem; }
  .edit-free-toggle { font-size: 0.68rem !important; }
  .user-detail-meta { gap: 0.4rem; }
  .purchased-course-tag { max-width: 180px; }
  .course-tree-actions { flex-wrap: wrap; gap: 0.3rem; }
}

/* ============================================================
   TOP ANNOUNCEMENT BAR
   ============================================================ */
.top-announcement-bar {
  background: linear-gradient(90deg, var(--color-primary), var(--color-primary-hover));
  color: rgba(255,255,255,0.95);
  padding: 0.5rem 5%;
  font-size: 0.78rem;
  font-weight: 600;
}
.top-bar-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.top-bar-inner i { margin-right: 0.35rem; opacity: 0.9; }
[data-theme="dark"] .top-announcement-bar { background: linear-gradient(90deg, #0D47A1, #1565C0); }
@media (max-width: 639px) {
  .top-announcement-bar { padding: 0.4rem 1rem; font-size: 0.72rem; }
  .top-bar-inner span:last-child { display: none; }
}

/* ============================================================
   STATS BAR
   ============================================================ */
.stats-bar {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-hover) 100%);
  border-radius: var(--radius-lg);
  padding: 1.25rem 2rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 4px 20px rgba(21,101,192,0.3);
}
.stats-bar-inner {
  display: flex;
  align-items: center;
  justify-content: center;
}
.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.2rem;
  flex: 1;
  padding: 0.25rem 1rem;
}
.stat-number {
  font-size: 1.85rem;
  font-weight: 800;
  color: #FFFFFF;
  line-height: 1;
  font-family: var(--font-heading);
}
.stat-label {
  font-size: 0.76rem;
  font-weight: 700;
  color: rgba(255,255,255,0.82);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
}
.stat-divider {
  width: 1px;
  height: 44px;
  background: rgba(255,255,255,0.28);
  flex-shrink: 0;
}
@media (max-width: 639px) {
  .stats-bar { padding: 1rem; border-radius: var(--radius-md); }
  .stat-item { padding: 0.2rem 0.6rem; }
  .stat-number { font-size: 1.3rem; }
  .stat-label { font-size: 0.65rem; }
}

/* ============================================================
   FEATURES SECTION
   ============================================================ */
.features-section {
  margin-top: 3.5rem;
  padding-top: 2.5rem;
  border-top: 1px solid var(--border-color);
}
.features-title {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}
.features-subtitle {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.92rem;
  font-weight: 600;
  margin-bottom: 2rem;
}
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}
.feature-card {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.25rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: rgba(21,101,192,0.25);
}
.feature-icon {
  width: 58px; height: 58px;
  border-radius: 50%;
  background: linear-gradient(135deg, rgba(21,101,192,0.1), rgba(21,101,192,0.06));
  border: 1.5px solid rgba(21,101,192,0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem;
  font-size: 1.35rem;
  color: var(--color-primary);
  transition: all var(--transition-fast);
}
.feature-card:hover .feature-icon {
  background: var(--color-primary);
  color: #FFFFFF;
  border-color: var(--color-primary);
  transform: scale(1.06);
}
.feature-card h4 {
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}
.feature-card p {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 500;
  line-height: 1.6;
}
@media (max-width: 639px) {
  .features-section { margin-top: 2.5rem; padding-top: 2rem; }
  .features-grid { grid-template-columns: repeat(2, 1fr); gap: 0.875rem; }
  .feature-card { padding: 1.25rem 0.875rem; }
  .features-title { font-size: 1.25rem; }
  .feature-icon { width: 48px; height: 48px; font-size: 1.15rem; }
}
@media (min-width: 640px) and (max-width: 1023px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ============================================================
   COURSE CARD — CTA BUTTON
   ============================================================ */
.course-cta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.7rem 1.25rem;
  background: linear-gradient(90deg, var(--color-primary), var(--color-primary-hover));
  color: #FFFFFF;
  font-size: 0.875rem;
  font-weight: 700;
  transition: all var(--transition-fast);
  letter-spacing: 0.01em;
}
.course-cta i {
  transition: transform var(--transition-fast);
}
.course-card:hover .course-cta {
  background: linear-gradient(90deg, var(--color-primary-hover), #062E84);
}
.course-card:hover .course-cta i {
  transform: translateX(5px);
}

/* ============================================================
   SITE FOOTER
   ============================================================ */
.site-footer {
  background: linear-gradient(135deg, #1E293B 0%, #0F172A 100%);
  color: rgba(255,255,255,0.8);
  margin-top: 3rem;
  padding: 2.5rem 5%;
}
[data-theme="dark"] .site-footer {
  background: rgba(15,23,42,0.98);
  border-top: 1px solid rgba(255,255,255,0.06);
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
}
.footer-top {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.875rem;
  text-align: center;
  margin-bottom: 1.5rem;
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.45rem;
  font-weight: 800;
  color: #FFFFFF;
}
.footer-brand i {
  color: var(--color-primary);
}
.footer-tagline {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.6);
  font-weight: 500;
  max-width: 480px;
  line-height: 1.5;
}
.footer-contact {
  display: flex;
  align-items: center;
  gap: 1.75rem;
  flex-wrap: wrap;
  justify-content: center;
  font-size: 0.82rem;
  color: rgba(255,255,255,0.7);
  font-weight: 600;
}
.footer-contact i {
  color: var(--color-primary);
  margin-right: 0.3rem;
}
.footer-divider {
  height: 1px;
  background: rgba(255,255,255,0.08);
  margin-bottom: 1.25rem;
}
.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.875rem;
}
.footer-copy {
  font-size: 0.78rem;
  color: rgba(255,255,255,0.4);
  font-weight: 500;
}
.footer-grades {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.footer-grades span {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.2rem 0.65rem;
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: var(--radius-full);
  color: rgba(255,255,255,0.55);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.footer-grades span:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* ============================================================
   MAIN NAV TABS (Khóa học / Luyện đề)
   ============================================================ */
.main-nav-tabs {
  display: flex;
  align-items: stretch;
  gap: 0;
  flex: 1;
  padding: 0 0.5rem;
  align-self: stretch;
}
.main-nav-tab {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0 1.1rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast);
  user-select: none;
  white-space: nowrap;
}
.main-nav-tab:hover { color: var(--color-primary); }
.main-nav-tab.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}
.main-nav-tab i { font-size: 0.85rem; }
@media (max-width: 480px) {
  .main-nav-tab { padding: 0 0.7rem; font-size: 0.8rem; }
}

/* ============================================================
   MOBILE BOTTOM NAVIGATION (≤639px)
   ============================================================ */

/* Desktop: ẩn hoàn toàn */
.mobile-bottom-nav {
  display: none;
}

@media (max-width: 639px) {
  .mobile-bottom-nav {
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    /* z-index cao để luôn nổi trên mọi nội dung */
    z-index: 9000;
    background: var(--bg-surface-solid);
    border-top: 1.5px solid var(--border-color);
    box-shadow: 0 -2px 16px rgba(0,0,0,0.10);
    /* Safe area cho iPhone có notch/home indicator */
    padding-bottom: env(safe-area-inset-bottom, 0px);
    /* Quan trọng: buộc trình duyệt tạo layer riêng — fix iOS Safari touch bug */
    -webkit-transform: translateZ(0);
    transform: translateZ(0);
    will-change: transform;
    /* Đảm bảo click/touch luôn hoạt động */
    pointer-events: auto;
  }

  .mob-nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 4px;
    padding: 10px 4px 8px;
    /* Font rõ ràng, không kế thừa gì bị vỡ */
    font-family: 'Nunito', system-ui, -apple-system, sans-serif;
    font-size: 11px;
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-muted);
    /* Touch-friendly */
    cursor: pointer;
    touch-action: manipulation;     /* bỏ độ trễ 300ms trên mobile */
    -webkit-tap-highlight-color: transparent;
    user-select: none;
    position: relative;
    transition: color 0.15s ease;
    /* Đảm bảo nhận click */
    pointer-events: auto;
    -webkit-user-select: none;
  }

  .mob-nav-item i {
    font-size: 20px;
    line-height: 1;
    display: block;
    transition: transform 0.15s ease, color 0.15s ease;
  }

  .mob-nav-item span {
    display: block;
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 0.01em;
    white-space: nowrap;
  }

  /* Feedback khi nhấn */
  .mob-nav-item:active {
    background: rgba(21,101,192,0.07);
  }
  .mob-nav-item:active i {
    transform: scale(0.88);
  }

  /* Tab đang active */
  .mob-nav-item.active {
    color: var(--color-primary);
  }
  .mob-nav-item.active i {
    transform: translateY(-2px) scale(1.08);
  }

  /* Gạch chân trên tab active */
  .mob-nav-item.active::before {
    content: '';
    position: absolute;
    top: 0;
    left: 18%;
    right: 18%;
    height: 3px;
    background: var(--color-primary);
    border-radius: 0 0 4px 4px;
  }
  /* Ẩn bottom nav khi có modal mở — fix iOS Safari z-index bug */
  html:has(.modal-overlay.active) #mobile-bottom-nav {
    display: none !important;
  }
}

/* ============================================================
   LUYỆN ĐỀ — DANH SÁCH ĐỀ
   ============================================================ */
.ld-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.ld-filters {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}
.ld-filters .filter-select { min-width: 130px; }

/* Date input with picker button */
.date-input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}
.date-input-wrap .form-control {
  padding-right: 2.6rem;
}
.date-hidden-picker {
  position: absolute;
  right: 2.2rem;
  top: 50%;
  transform: translateY(-50%);
  width: 0;
  height: 0;
  opacity: 0;
  pointer-events: none;
  border: none;
  padding: 0;
}
.date-picker-btn {
  position: absolute;
  right: 0.5rem;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-primary);
  font-size: 1rem;
  padding: 0.2rem 0.3rem;
  border-radius: var(--radius-sm);
  transition: background 0.15s;
}
.date-picker-btn:hover { background: rgba(21,101,192,0.1); }

.ld-grade-pills {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
  padding: 0.75rem 1rem;
  background: var(--bg-card);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
}
.ld-grade-pill {
  padding: 0.5rem 1.1rem;
  border-radius: 999px;
  border: 2px solid var(--border-color);
  background: var(--bg-surface);
  color: var(--text-muted);
  font-size: 0.88rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s ease;
  font-family: var(--font-body);
  white-space: nowrap;
}
.ld-grade-pill:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: rgba(21,101,192,0.07);
}
.ld-grade-pill.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(21,101,192,0.3);
}

.exam-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.2rem;
}
.exam-card {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), transform var(--transition-fast);
  cursor: pointer;
}
.exam-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.exam-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
}
.exam-card-title {
  font-size: 0.97rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.4;
  flex: 1;
}
.exam-difficulty {
  display: flex;
  gap: 2px;
  flex-shrink: 0;
}
.exam-difficulty i { font-size: 0.72rem; color: #E5E7EB; }
.exam-difficulty i.filled { color: #F59E0B; }
.exam-meta {
  display: flex;
  gap: 0.8rem;
  flex-wrap: wrap;
}
.exam-meta-item {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 600;
}
.exam-meta-item i { color: var(--color-primary); font-size: 0.75rem; }
.exam-tags { display: flex; gap: 0.4rem; flex-wrap: wrap; }
.exam-tag {
  padding: 0.15rem 0.55rem;
  border-radius: var(--radius-full);
  font-size: 0.72rem;
  font-weight: 700;
  background: rgba(21,101,192,0.1);
  color: var(--color-primary);
}
.exam-card-footer {
  margin-top: auto;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.exam-attempt-count { font-size: 0.78rem; color: var(--text-muted); font-weight: 600; }

/* ============================================================
   LUYỆN ĐỀ — MÀN HÌNH LÀM ĐỀ
   ============================================================ */
.exam-player-wrap {
  max-width: 760px;
  margin: 0 auto;
}
.exam-player-header {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}
.exam-player-title { font-size: 1rem; font-weight: 700; color: var(--text-main); }
.exam-timer {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--color-primary);
  background: rgba(21,101,192,0.08);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
}
.exam-timer.warning { color: #EF4444; background: rgba(239,68,68,0.08); }
.exam-progress-bar-wrap {
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.exam-progress-bar-track {
  flex: 1;
  height: 8px;
  background: var(--border-color);
  border-radius: var(--radius-full);
  overflow: hidden;
}
.exam-progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-full);
  transition: width 0.3s ease;
}
.exam-progress-label { font-size: 0.8rem; font-weight: 700; color: var(--text-muted); white-space: nowrap; }

.exam-question-card {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
}
.exam-question-num {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.6rem;
}
.exam-question-content {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.55;
  margin-bottom: 1.25rem;
}
.exam-options { display: flex; flex-direction: column; gap: 0.65rem; }
.exam-option {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding: 0.8rem 1rem;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  background: var(--bg-surface-solid);
  transition: border-color var(--transition-fast), background var(--transition-fast);
  user-select: none;
}
.exam-option:hover { border-color: var(--color-primary); background: rgba(21,101,192,0.04); }
.exam-option.selected {
  border-color: var(--color-primary);
  background: rgba(21,101,192,0.08);
  color: var(--color-primary);
}
.exam-option.correct  { border-color: #10B981; background: rgba(16,185,129,0.08); color: #065F46; }
.exam-option.wrong    { border-color: #EF4444; background: rgba(239,68,68,0.08);  color: #991B1B; }
.exam-option-letter {
  width: 1.7rem; height: 1.7rem;
  border-radius: 50%;
  border: 1.5px solid currentColor;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem; font-weight: 800;
  flex-shrink: 0;
}
.exam-fill-input {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 1.1rem;
  font-weight: 700;
  text-align: center;
  color: var(--text-main);
  background: var(--bg-surface-solid);
  outline: none;
  transition: border-color var(--transition-fast);
}
.exam-fill-input:focus { border-color: var(--color-primary); box-shadow: 0 0 0 3px rgba(21,101,192,0.12); }
.exam-truefalse-options { display: flex; gap: 1rem; }
.exam-truefalse-options .exam-option { flex: 1; justify-content: center; font-size: 1rem; }

.exam-explanation {
  margin-top: 1rem;
  padding: 0.85rem 1rem;
  background: rgba(16,185,129,0.07);
  border-left: 3px solid #10B981;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.88rem;
  color: var(--text-main);
  display: none;
}
.exam-explanation.visible { display: block; }

.exam-nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
}
.exam-question-dots {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  flex: 1;
  justify-content: center;
}
.exam-q-dot {
  width: 2rem; height: 2rem;
  border-radius: 50%;
  border: 1.5px solid var(--border-color);
  background: var(--bg-surface-solid);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem; font-weight: 700;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition-fast);
}
.exam-q-dot:hover { border-color: var(--color-primary); color: var(--color-primary); }
.exam-q-dot.answered { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.exam-q-dot.current  { border-color: var(--color-primary); color: var(--color-primary); box-shadow: 0 0 0 2px rgba(21,101,192,0.25); }

/* ============================================================
   LUYỆN ĐỀ — KẾT QUẢ
   ============================================================ */
.exam-result-wrap {
  max-width: 680px;
  margin: 0 auto;
}
.exam-result-hero {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-hover));
  color: #fff;
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  margin-bottom: 1.5rem;
}
.exam-result-score {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1;
}
.exam-result-label {
  font-size: 1.1rem;
  font-weight: 700;
  opacity: 0.9;
  margin-top: 0.4rem;
}
.exam-result-grade {
  display: inline-block;
  margin-top: 0.75rem;
  padding: 0.3rem 1.1rem;
  background: rgba(255,255,255,0.2);
  border-radius: var(--radius-full);
  font-size: 1rem;
  font-weight: 800;
}
.exam-result-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.exam-result-stat {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  text-align: center;
}
.exam-result-stat-num { font-size: 1.8rem; font-weight: 800; }
.exam-result-stat-num.correct { color: #10B981; }
.exam-result-stat-num.wrong   { color: #EF4444; }
.exam-result-stat-num.skipped { color: var(--text-muted); }
.exam-result-stat-label { font-size: 0.8rem; font-weight: 600; color: var(--text-muted); margin-top: 0.25rem; }
.exam-result-review { margin-bottom: 1.5rem; }
.exam-result-review-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.85rem;
  color: var(--text-main);
}
.exam-review-item {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin-bottom: 0.6rem;
}
.exam-review-item.correct-item { border-left: 4px solid #10B981; }
.exam-review-item.wrong-item   { border-left: 4px solid #EF4444; }
.exam-review-item.skip-item    { border-left: 4px solid var(--text-muted); }
.exam-review-item-header {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 0.5rem;
}
.exam-review-icon { font-size: 0.9rem; }
.exam-review-icon.c { color: #10B981; }
.exam-review-icon.w { color: #EF4444; }
.exam-review-icon.s { color: var(--text-muted); }
.exam-review-q-text { font-size: 0.9rem; font-weight: 700; color: var(--text-main); flex: 1; }
.exam-review-answer {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 0.3rem;
}
.exam-review-answer span.green { color: #10B981; font-weight: 700; }
.exam-review-answer span.red   { color: #EF4444; font-weight: 700; }

/* Badge tích/X tròn */
.exam-review-icon-badge {
  width: 2rem; height: 2rem;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.95rem;
  font-weight: 800;
  flex-shrink: 0;
}
.exam-review-icon-badge.correct { background: #DCFCE7; color: #16A34A; }
.exam-review-icon-badge.wrong   { background: #FEE2E2; color: #DC2626; }
.exam-review-icon-badge.skip    { background: var(--bg-surface-hover); color: var(--text-muted); }

/* Options trong review kết quả */
.exam-review-options { display: flex; flex-direction: column; gap: 0.35rem; margin-top: 0.5rem; }
.exam-review-opt {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.45rem 0.75rem;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--border-color);
  background: var(--bg-surface-solid);
  font-size: 0.85rem;
  color: var(--text-main);
}
.exam-review-opt.correct { border-color: #10B981; background: rgba(16,185,129,0.09); color: #065F46; font-weight: 700; }
.exam-review-opt.wrong   { border-color: #EF4444; background: rgba(239,68,68,0.08);  color: #991B1B; font-weight: 700; }
.exam-review-opt-letter {
  width: 1.45rem; height: 1.45rem;
  border-radius: 50%;
  border: 1.5px solid currentColor;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.72rem;
  font-weight: 800;
  flex-shrink: 0;
}

/* Điền số trong review */
.exam-review-fill { margin-top: 0.5rem; display: flex; flex-direction: column; gap: 0.3rem; }
.exam-review-fill-row { display: flex; align-items: center; gap: 0.6rem; font-size: 0.83rem; color: var(--text-muted); }
.exam-review-fill-ans {
  font-weight: 800;
  padding: 0.18rem 0.65rem;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}
.exam-review-fill-ans.correct { background: #DCFCE7; color: #16A34A; }
.exam-review-fill-ans.wrong   { background: #FEE2E2; color: #DC2626; }
.exam-review-fill-ans.skip    { background: var(--bg-surface-hover); color: var(--text-muted); }

/* Giải thích */
.exam-review-explanation {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: #92400E;
  font-weight: 600;
  padding: 0.4rem 0.75rem;
  background: #FEF3C7;
  border-radius: var(--radius-sm);
  border-left: 3px solid #F59E0B;
}

.exam-result-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}
.exam-result-actions .btn { flex: 1; min-width: 130px; }

/* ============================================================
   ADMIN EXAM MANAGEMENT
   ============================================================ */
.admin-exam-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}
.admin-exam-list { display: flex; flex-direction: column; gap: 0.6rem; }
.admin-exam-row {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}
.admin-exam-row:hover { border-color: var(--color-primary); }
.admin-exam-info { flex: 1; min-width: 0; }
.admin-exam-title { font-weight: 700; font-size: 0.92rem; color: var(--text-main); }
.admin-exam-meta-row {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 600;
  margin-top: 0.2rem;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}
.admin-exam-actions { display: flex; gap: 0.4rem; flex-shrink: 0; }

/* Admin exam 2-tab nav */
.admin-exam-tabs-nav {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border-color);
  margin-bottom: 1.25rem;
}
.admin-exam-tab-btn {
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  padding: 0.55rem 1.2rem;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  margin-bottom: -2px;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
}
.admin-exam-tab-btn:hover { color: var(--text-main); background: var(--bg-surface-hover); }
.admin-exam-tab-btn.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  background: var(--bg-surface-hover);
}

.exam-form-section {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-bottom: 1.25rem;
}
.exam-form-section-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.exam-question-builder {
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin-bottom: 0.75rem;
  background: var(--bg-app);
}
.exam-question-builder-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}
.exam-q-num-badge {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--color-primary);
  background: rgba(21,101,192,0.1);
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
}
.exam-option-inputs { display: flex; flex-direction: column; gap: 0.4rem; margin-top: 0.5rem; }
.exam-option-row { display: flex; align-items: center; gap: 0.5rem; }
.exam-option-row input[type="radio"],
.exam-option-row input[type="checkbox"] { flex-shrink: 0; accent-color: var(--color-primary); width: 1rem; height: 1rem; }
.exam-option-row input[type="text"] { flex: 1; }
.exam-option-row label { font-size: 0.82rem; font-weight: 700; color: var(--text-muted); width: 1.4rem; flex-shrink: 0; }
@media (max-width: 639px) {
  .site-footer { padding: 2rem 1.25rem 1.5rem; }
  .footer-contact { gap: 0.875rem; }
  .footer-bottom { flex-direction: column; align-items: center; text-align: center; }
}

/* Ẩn footer khi không ở trang chủ — được bật/tắt qua JS */
.site-footer.hidden { display: none; }

/* ============================================================
   PHÂN TRANG ADMIN (Pagination)
   ============================================================ */
.admin-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  padding: 0.75rem 0;
  margin-top: 0.5rem;
}
.admin-page-btn {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-sm);
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--color-primary);
  font-size: 0.8rem;
  transition: background 0.15s, border-color 0.15s;
}
.admin-page-btn:hover:not(:disabled) { background: var(--bg-surface-hover); border-color: var(--color-primary); }
.admin-page-btn:disabled { opacity: 0.4; cursor: default; }
.admin-page-info { font-size: 0.82rem; font-weight: 700; color: var(--text-muted); }

/* ============================================================
   MÀN HÌNH XÁC NHẬN BẮT ĐẦU LÀM BÀI
   ============================================================ */
.exam-start-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  padding: 2rem 1rem;
}
.exam-start-card {
  background: var(--bg-surface-solid);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2rem;
  max-width: 520px;
  width: 100%;
  text-align: center;
  box-shadow: var(--shadow-md);
}
.exam-start-icon {
  font-size: 3rem;
  color: var(--color-primary);
  margin-bottom: 1rem;
}
.exam-start-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 1.25rem;
  line-height: 1.35;
}
.exam-start-meta {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}
.exam-start-meta-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-muted);
  background: var(--bg-app);
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius-full);
}
.exam-start-meta-item i { color: var(--color-primary); }
.exam-start-desc {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  line-height: 1.6;
}
.exam-start-notice {
  background: #FEF3C7;
  border: 1.5px solid #FDE68A;
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  font-size: 0.85rem;
  color: #92400E;
  font-weight: 600;
  text-align: left;
  margin-bottom: 1.5rem;
  line-height: 1.5;
}
.exam-start-notice i { color: #D97706; margin-right: 0.3rem; }
.exam-start-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}
.exam-gate-form {
  background: var(--bg-surface-hover);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

/* ============================================================
   HỆ THỐNG NẠP TIỀN & MUA KHÓA HỌC
   ============================================================ */

/* Badge số dư trong dropdown */
.user-balance-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  background: linear-gradient(135deg, var(--color-success), #16a34a);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  letter-spacing: 0.01em;
}

/* Badge số yêu cầu nạp tiền chờ duyệt */
.topup-pending-badge {
  background: var(--color-danger);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 800;
  padding: 0.1rem 0.4rem;
  border-radius: 999px;
  margin-left: auto;
  line-height: 1.4;
}

/* Nút nạp tiền trong dropdown */
.user-dropdown-item.topup-item {
  color: var(--color-success);
  font-weight: 800;
}
.user-dropdown-item.topup-item:hover {
  background: #d1fae5;
  color: #065f46;
}

/* ── Topup Modal — Bước 1: Chọn số tiền ── */
.topup-amount-presets {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.6rem;
  margin-bottom: 1rem;
}
.topup-preset-btn {
  padding: 0.65rem;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  color: var(--text-main);
  font-weight: 800;
  font-size: 0.92rem;
  cursor: pointer;
  text-align: center;
  transition: all var(--transition-fast);
  font-family: var(--font-body);
}
.topup-preset-btn:hover,
.topup-preset-btn.selected {
  border-color: var(--color-success);
  background: #d1fae5;
  color: #065f46;
}
[data-theme="dark"] .topup-preset-btn:hover,
[data-theme="dark"] .topup-preset-btn.selected {
  background: #064e3b;
  color: #6ee7b7;
}

/* ── Topup Modal — Bước 2: Thông tin chuyển khoản ── */
.topup-bank-info-card {
  background: var(--bg-surface-solid);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.2rem;
  margin-bottom: 1rem;
}
.topup-bank-info-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0;
  border-bottom: 1px dashed var(--border-color);
}
.topup-bank-info-row:last-child { border-bottom: none; }
.topup-bank-label {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-muted);
  flex-shrink: 0;
}
.topup-bank-value {
  font-weight: 800;
  font-size: 0.95rem;
  color: var(--text-main);
  text-align: right;
  word-break: break-all;
}
.topup-code-highlight {
  font-size: 1.1rem;
  font-weight: 900;
  color: var(--color-primary);
  letter-spacing: 0.05em;
  background: #ede9fe;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
}
[data-theme="dark"] .topup-code-highlight {
  background: #2e1065;
  color: #c4b5fd;
}
.topup-amount-highlight {
  font-size: 1.15rem;
  font-weight: 900;
  color: var(--color-success);
}
.topup-copy-btn {
  background: none;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.2rem 0.5rem;
  cursor: pointer;
  color: var(--text-muted);
  font-size: 0.78rem;
  font-weight: 700;
  transition: all var(--transition-fast);
  flex-shrink: 0;
  font-family: var(--font-body);
}
.topup-copy-btn:hover { border-color: var(--color-primary); color: var(--color-primary); }

.topup-qr-wrap {
  text-align: center;
  margin-bottom: 1rem;
}
.topup-qr-wrap img {
  border-radius: var(--radius-md);
  border: 2px solid var(--border-color);
  max-width: 200px;
  width: 100%;
}
.topup-warning-box {
  background: #fefce8;
  border: 2px solid #fde047;
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: #713f12;
  line-height: 1.5;
  margin-bottom: 1rem;
}
[data-theme="dark"] .topup-warning-box {
  background: #292524;
  border-color: #a16207;
  color: #fef3c7;
}

/* ── Admin: Cài đặt ngân hàng ── */
.topup-bank-settings-card {
  background: var(--bg-surface-solid);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin-bottom: 1.5rem;
}
.topup-bank-settings-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.2rem;
  cursor: pointer;
  font-weight: 800;
  font-size: 0.95rem;
  color: var(--text-main);
  background: var(--bg-surface-hover);
  user-select: none;
  gap: 0.5rem;
}
.topup-bank-settings-header:hover { background: var(--bg-surface-solid); }
#topup-bank-settings-body {
  padding: 0 1.2rem 1rem;
}

/* ── Admin: Tabs yêu cầu ── */
.topup-req-tabs {
  display: flex;
  gap: 0.5rem;
}
.topup-req-tab {
  padding: 0.5rem 1.1rem;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  color: var(--text-muted);
  font-weight: 800;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-body);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.topup-req-tab.active {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: #ede9fe;
}
[data-theme="dark"] .topup-req-tab.active { background: #2e1065; }
.topup-tab-count {
  background: var(--color-danger);
  color: #fff;
  font-size: 0.72rem;
  font-weight: 900;
  padding: 0.05rem 0.38rem;
  border-radius: 999px;
}

/* ── Admin: Request row ── */
.topup-req-row {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 1rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface-solid);
  margin-bottom: 0.6rem;
  flex-wrap: wrap;
}
.topup-req-row.confirmed { border-color: var(--color-success); background: #f0fdf4; }
.topup-req-row.rejected  { border-color: var(--color-danger);  opacity: 0.75; }
[data-theme="dark"] .topup-req-row.confirmed { background: #052e16; }
.topup-req-info { flex: 1; min-width: 200px; }
.topup-req-name { font-weight: 800; font-size: 0.95rem; margin-bottom: 0.2rem; }
.topup-req-meta { font-size: 0.8rem; color: var(--text-muted); font-weight: 700; line-height: 1.6; }
.topup-req-amount {
  font-weight: 900;
  font-size: 1.1rem;
  color: var(--color-success);
  white-space: nowrap;
  flex-shrink: 0;
}
.topup-req-actions { display: flex; gap: 0.5rem; align-items: center; flex-shrink: 0; }
.topup-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.78rem;
  font-weight: 800;
  padding: 0.25rem 0.6rem;
  border-radius: 999px;
}
.topup-status-badge.pending  { background: #fef9c3; color: #713f12; }
.topup-status-badge.confirmed { background: #dcfce7; color: #14532d; }
.topup-status-badge.rejected  { background: #fee2e2; color: #7f1d1d; }
[data-theme="dark"] .topup-status-badge.pending   { background: #292524; color: #fef3c7; }
[data-theme="dark"] .topup-status-badge.confirmed { background: #052e16; color: #86efac; }
[data-theme="dark"] .topup-status-badge.rejected  { background: #450a0a; color: #fca5a5; }

/* ── Course card: giá + nút mua ── */
.course-price-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  background: var(--color-primary);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.25rem 0.6rem;
  border-radius: 999px;
  margin-top: 0.25rem;
}
.course-card-buy-btn {
  width: 100%;
  margin-top: 0.75rem;
  padding: 0.6rem;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 800;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-body);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
}
.course-card-buy-btn:hover { background: var(--color-primary-dark, #4f46e5); transform: translateY(-1px); }

/* ── Purchase Modal ── */
.purchase-course-thumb {
  width: 100%;
  height: 140px;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: 1rem;
}
.purchase-balance-status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.75rem 1rem;
  background: var(--bg-surface-hover);
  border-radius: var(--radius-md);
  margin-top: 1rem;
  font-weight: 700;
  font-size: 0.92rem;
}
.purchase-balance-ok   { color: var(--color-success); }
.purchase-balance-fail { color: var(--color-danger); }

/* ── Video locked: nút mua ── */
.video-locked-buy-btn {
  margin-top: 1rem;
  padding: 0.7rem 1.8rem;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 800;
  font-size: 1rem;
  cursor: pointer;
  font-family: var(--font-body);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all var(--transition-fast);
}
.video-locked-buy-btn:hover { opacity: 0.85; transform: translateY(-1px); }

@media (max-width: 639px) {
  .topup-amount-presets { grid-template-columns: repeat(2, 1fr); }
  .topup-req-row { flex-wrap: wrap; }
}


/* ============================================================
   WALLET PANEL — Ví của tôi
   ============================================================ */
.wallet-tx-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.wallet-tx-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.85rem;
  transition: background var(--transition-fast);
}
.wallet-tx-row:last-child { border-bottom: none; }
.wallet-tx-row:hover { background: var(--bg-surface-hover); }

/* ============================================================
   LUYỆN ĐỀ — Grade & Type sections
   ============================================================ */
.ld-grade-section {
  margin-bottom: 2rem;
}
.ld-grade-header {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-main);
  padding: 0.6rem 0.9rem;
  background: var(--bg-surface-solid);
  border-left: 4px solid var(--color-primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.ld-type-block {
  margin-bottom: 1.25rem;
}
.ld-type-header {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.9rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.7rem;
  padding-bottom: 0.4rem;
  border-bottom: 2px dashed var(--border-color);
}
.ld-type-count {
  margin-left: auto;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-muted);
  background: var(--bg-surface-hover);
  border-radius: 99px;
  padding: 0.1rem 0.55rem;
}

/* ============================================================
   ADMIN — Bài làm học sinh (Exam Attempts)
   ============================================================ */
.attempt-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.5rem;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 0.5rem;
  background: var(--bg-surface-solid);
  transition: background var(--transition-fast);
}
.attempt-row:hover { background: var(--bg-surface-hover); }
.attempt-row-main { display: flex; flex-direction: column; gap: 0.25rem; }
.attempt-row-actions { display: flex; align-items: flex-start; gap: 0.3rem; }
.attempt-student { display: flex; align-items: center; gap: 0.4rem; font-size: 0.85rem; }
.attempt-exam-title { font-size: 0.8rem; color: var(--text-muted); font-weight: 600; }
.attempt-feedback-display {
  font-size: 0.8rem;
  color: var(--color-primary);
  font-weight: 700;
  font-style: italic;
  margin-top: 0.2rem;
}