/* ============================================
   CPP LIBRARY - ITLAND Brand | Light/Dark Theme
   Default: Light | Thư viện C++ đẳng cấp
   ============================================ */

/* === LIGHT THEME (default) === */
:root,
body.theme-light {
  --bg-primary: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-tertiary: #e2e8f0;
  --bg-card: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --accent-cpp: #0ea5e9;
  --accent-success: #22c55e;
  --accent-warning: #f59e0b;
  --accent-danger: #ef4444;
  --border: #e2e8f0;
  --font-sans: 'JetBrains Mono', 'Fira Code', 'Source Code Pro', monospace;
  --font-display: 'Space Grotesk', 'Inter', system-ui, sans-serif;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-strong: 0 8px 32px rgba(0,0,0,0.12);
  --transition: 0.2s ease;
}

/* === DARK THEME === */
body.theme-dark {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-card: #1c2128;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent-cpp: #79c0ff;
  --accent-success: #3fb950;
  --accent-warning: #d29922;
  --accent-danger: #f85149;
  --border: #30363d;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-strong: 0 8px 32px rgba(0,0,0,0.5);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: radial-gradient(ellipse 80% 50% at 50% -20%, rgba(14, 165, 233, 0.06), transparent),
    linear-gradient(180deg, var(--bg-primary) 0%, #f1f5f9 100%);
  pointer-events: none;
  z-index: -1;
}

body.theme-dark::before {
  background: radial-gradient(ellipse 80% 50% at 50% -20%, rgba(121, 192, 255, 0.08), transparent),
    linear-gradient(180deg, var(--bg-primary) 0%, #0a0e12 100%);
}

a {
  color: var(--accent-cpp);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: #0284c7; text-decoration: underline; }
body.theme-dark a:hover { color: #58a6ff; }

/* Navigation - moved to nav.css (topbar + dropdown + sidebar) */

/* Theme toggle */
.btn-theme {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 1.2rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}
.btn-theme:hover { background: var(--bg-tertiary); }

/* Nút chia sẻ - thống nhất toàn site (light bg, rounded, dark icon) */
.btn-share,
.btn-icon.btn-share,
#btnShare.btn-icon,
.store-detail-btn[title="Chia sẻ"],
button[title="Chia sẻ"],
button[title="Share"] {
  background: #f1f5f9 !important;
  border: 1px solid #e2e8f0 !important;
  border-radius: 10px !important;
  color: #475569 !important;
  box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}
.btn-share:hover,
.btn-icon.btn-share:hover,
#btnShare.btn-icon:hover,
.store-detail-btn[title="Chia sẻ"]:hover,
button[title="Chia sẻ"]:hover,
button[title="Share"]:hover {
  background: #e2e8f0 !important;
  border-color: #cbd5e1 !important;
  color: #334155 !important;
  box-shadow: 0 2px 4px rgba(0,0,0,0.08);
}
.btn-share i,
.btn-icon.btn-share i,
#btnShare.btn-icon i,
.store-detail-btn[title="Chia sẻ"] i,
button[title="Chia sẻ"] i,
button[title="Share"] i {
  color: #475569 !important;
}
.btn-share:hover i,
.btn-icon.btn-share:hover i,
#btnShare.btn-icon:hover i,
.store-detail-btn[title="Chia sẻ"]:hover i,
button[title="Chia sẻ"]:hover i,
button[title="Share"]:hover i {
  color: #334155 !important;
}
body.theme-dark .btn-share,
body.theme-dark .btn-icon.btn-share,
body.theme-dark #btnShare.btn-icon,
body.theme-dark .store-detail-btn[title="Chia sẻ"],
body.theme-dark button[title="Chia sẻ"],
body.theme-dark button[title="Share"] {
  background: #21262d !important;
  border-color: #30363d !important;
  color: #8b949e !important;
}
body.theme-dark .btn-share:hover,
body.theme-dark .btn-icon.btn-share:hover,
body.theme-dark #btnShare.btn-icon:hover,
body.theme-dark .store-detail-btn[title="Chia sẻ"]:hover,
body.theme-dark button[title="Chia sẻ"]:hover,
body.theme-dark button[title="Share"]:hover {
  background: #30363d !important;
  border-color: #484f58 !important;
  color: #c9d1d9 !important;
}
body.theme-dark .btn-share i,
body.theme-dark .btn-icon.btn-share i,
body.theme-dark #btnShare.btn-icon i,
body.theme-dark .store-detail-btn[title="Chia sẻ"] i,
body.theme-dark button[title="Chia sẻ"] i,
body.theme-dark button[title="Share"] i {
  color: #8b949e !important;
}
body.theme-dark .btn-share:hover i,
body.theme-dark .btn-icon.btn-share:hover i,
body.theme-dark #btnShare.btn-icon:hover i,
body.theme-dark .store-detail-btn[title="Chia sẻ"]:hover i,
body.theme-dark button[title="Chia sẻ"]:hover i,
body.theme-dark button[title="Share"]:hover i {
  color: #c9d1d9 !important;
}

/* Search bar */
.search-container {
  flex: 1;
  max-width: 400px;
  margin: 0 2rem;
  position: relative;
}
.search-input {
  width: 100%;
  padding: 0.5rem 1rem 0.5rem 2.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  transition: border-color var(--transition);
}
.search-input:focus { outline: none; border-color: var(--accent-cpp); }
.search-input::placeholder { color: var(--text-muted); }
.search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

.container { max-width: 1400px; margin: 0 auto; padding: 2rem; }

/* Hero */
.hero { text-align: center; padding: 4rem 2rem; margin-bottom: 3rem; }
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-cpp) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p { font-size: 1.2rem; color: var(--text-secondary); max-width: 600px; margin: 0 auto 2rem; }
.hero-stats { display: flex; justify-content: center; gap: 3rem; flex-wrap: wrap; margin-top: 2rem; }
.hero-stat { text-align: center; }
.hero-stat .number { font-size: 2rem; font-weight: 700; color: var(--accent-cpp); }
.hero-stat .label { font-size: 0.85rem; color: var(--text-muted); }

/* Cards */
.cards-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 1.5rem; }

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  transition: all var(--transition);
  cursor: pointer;
}
.card:hover {
  border-color: var(--accent-cpp);
  transform: translateY(-2px);
  box-shadow: var(--shadow-strong);
}

.card-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--accent-cpp) 0%, #0284c7 100%);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1rem;
}
body.theme-dark .card-icon { background: linear-gradient(135deg, var(--accent-cpp) 0%, #388bfd 100%); }

.card h3 { font-size: 1.2rem; margin-bottom: 0.5rem; }
.card p { color: var(--text-secondary); font-size: 0.9rem; }

/* Store - Ứng dụng & Tài liệu (apps, articles, videos) */
.store-tabs { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; flex-wrap: wrap; }
.store-tab {
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  border-radius: var(--radius);
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition);
}
.store-tab:hover { border-color: var(--accent-cpp); color: var(--accent-cpp); }
.store-tab.active { background: var(--accent-cpp); border-color: var(--accent-cpp); color: #fff; }
.store-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 360px), 1fr));
  gap: 1.5rem;
}
.store-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
}
.store-card:hover { border-color: var(--accent-cpp); box-shadow: var(--shadow-strong); }
.store-card-clickable { cursor: pointer; }
.store-card-clickable .store-card-header { cursor: pointer; }
.store-card-header {
  display: flex;
  gap: 1rem;
  padding: 1.25rem;
  color: inherit;
  text-decoration: none;
  transition: background var(--transition);
}
.store-card-header:hover { background: var(--bg-secondary); text-decoration: none; color: inherit; }
.store-card-icon {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--accent-cpp) 0%, #0284c7 100%);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  color: #fff;
}
.store-card-icon-img { width: 100%; height: 100%; object-fit: contain; }
.store-card-meta { flex: 1; min-width: 0; }
.store-card-meta h3 { font-size: 1.1rem; margin-bottom: 0.35rem; }
.store-card-meta p { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.5; }
.store-videos-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
  padding: 1rem 1.25rem;
  border-top: 1px solid var(--border);
}
.store-video-card {
  background: var(--bg-secondary);
  border-radius: var(--radius);
  overflow: hidden;
}
.store-video-wrap {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
}
.store-video-wrap iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}
.store-video-desc {
  padding: 0.75rem 1rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.4;
  margin: 0;
}
.store-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 0 1.25rem 1rem;
}
.store-link-tag {
  display: inline-block;
  padding: 0.25rem 0.6rem;
  background: var(--bg-tertiary);
  border-radius: 4px;
  font-size: 0.8rem;
  color: var(--accent-cpp);
  text-decoration: none;
  transition: all var(--transition);
}
.store-link-tag:hover { background: var(--accent-cpp); color: #fff; text-decoration: none; }
.store-load-more { text-align: center; margin-top: 1.5rem; }
.btn-load-more {
  padding: 0.75rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 0.95rem;
  cursor: pointer;
  transition: all var(--transition);
}
.btn-load-more:hover { border-color: var(--accent-cpp); color: var(--accent-cpp); }
body.theme-dark .store-card-icon { background: linear-gradient(135deg, var(--accent-cpp) 0%, #388bfd 100%); }

/* Store Detail Modal - full screen xem chi tiết */
.store-detail-modal {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-primary);
  z-index: 999999;
  overflow-y: auto;
  flex-direction: column;
}
.store-detail-modal.active { display: flex; }
.store-detail-modal-inner {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
}
.store-detail-modal-content {
  flex: 1;
  padding: 1.5rem 2rem 3rem;
}
.store-detail-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  padding: 1.25rem 2rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg-card);
  position: sticky;
  top: 0;
  z-index: 10;
}
.store-detail-header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0;
  color: var(--text-primary);
}
.store-detail-actions { display: flex; gap: 0.5rem; flex-shrink: 0; }
.store-detail-btn {
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  border-radius: var(--radius);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}
.store-detail-btn:hover { border-color: var(--accent-cpp); color: var(--accent-cpp); }
.store-detail-close:hover { border-color: var(--accent-danger); color: var(--accent-danger); }
.store-detail-body { padding-top: 1.5rem; }
.store-detail-desc {
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
  line-height: 1.7;
}
.store-detail-desc p { margin: 0 0 0.5rem; }
.store-detail-videos { margin-bottom: 2rem; }
.store-detail-videos h3,
.store-detail-links h3 {
  font-size: 1.1rem;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-primary);
}
.store-detail-videos h3 i,
.store-detail-links h3 i { color: var(--accent-cpp); }
.store-detail-videos-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1rem;
}
.store-detail-videos-grid .store-video-wrap { margin-bottom: 0; }
.store-detail-links { margin-top: 2rem; }
.store-detail-links-table { font-size: 0.9rem; }
.store-detail-download {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.6rem;
  background: var(--accent-cpp);
  color: #fff !important;
  border-radius: 4px;
  font-size: 0.85rem;
  text-decoration: none;
  transition: opacity var(--transition);
}
.store-detail-download:hover { opacity: 0.9; text-decoration: none; color: #fff !important; }
body.theme-dark .store-detail-download { background: var(--accent-cpp); }

.section { margin-bottom: 3rem; }
.section-title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--accent-cpp);
  display: inline-block;
}

.breadcrumb { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; font-size: 0.9rem; color: var(--text-muted); }
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb span { color: var(--text-muted); }

/* Wrapper cuộn ngang cho mọi bảng dữ liệu */
.resource-table-wrapper,
.table-scroll-wrapper {
  overflow-x: auto;
  margin-bottom: 1rem;
  min-width: 0;
}
.resource-table-wrapper {
  border: 2px solid #dc3545;
  border-radius: var(--radius-lg);
}

.resource-table {
  width: 100%;
  table-layout: auto;
  border-collapse: collapse;
  background: var(--bg-card);
}
.resource-table th, .resource-table td {
  padding: 1rem 1.5rem;
  text-align: left;
  border: 1px solid #dc3545;
  white-space: nowrap;
}
.resource-table th:first-child, .resource-table td:first-child {
  width: 1%;
  white-space: nowrap;
  text-align: center;
  min-width: 3rem;
}
.resource-table td:nth-child(4) { min-width: 8rem; }
.resource-table th { background: var(--bg-tertiary); color: var(--text-secondary); font-weight: 600; font-size: 0.85rem; }
.resource-table tr:last-child td { border-bottom: 1px solid #dc3545; }
.resource-table tr:hover td { background: rgba(14, 165, 233, 0.05); }
body.theme-dark .resource-table tr:hover td { background: rgba(121, 192, 255, 0.05); }

.file-badge {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  background: var(--bg-tertiary);
  border-radius: 4px;
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-right: 0.5rem;
}

.resource-links a { margin-right: 0.5rem; }

.pagination { display: flex; justify-content: center; gap: 0.5rem; margin-top: 2rem; flex-wrap: wrap; }
.pagination a, .pagination span {
  padding: 0.5rem 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 0.9rem;
}
.pagination a:hover { background: var(--bg-tertiary); border-color: var(--accent-cpp); text-decoration: none; }
.pagination .active { background: var(--accent-cpp); border-color: var(--accent-cpp); color: #fff; }

.tree-item { padding: 0.5rem 1rem; border-left: 3px solid transparent; margin-left: 1rem; transition: all var(--transition); display: flex; align-items: center; gap: 0.5rem; cursor: pointer; }
.tree-item:hover { background: var(--bg-secondary); border-left-color: var(--accent-cpp); }

.filter-bar { display: flex; gap: 1rem; margin-bottom: 1.5rem; flex-wrap: wrap; }
.filter-bar select, .filter-bar input {
  padding: 0.5rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: inherit;
}

/* Library smart table toolbar */
.library-table-toolbar {
  display: flex;
  gap: 1rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
  align-items: center;
}
.library-table-toolbar .table-search-input {
  flex: 1;
  min-width: 200px;
  padding: 0.5rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: inherit;
}
.library-table-toolbar .table-filter-select {
  padding: 0.5rem 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: inherit;
}
.library-table-toolbar .table-result-count {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-left: auto;
}
.resource-table th.sortable {
  cursor: pointer;
  user-select: none;
}
.resource-table th.sortable:hover {
  background: var(--bg-secondary) !important;
}
.library-empty {
  color: var(--text-muted);
  padding: 2rem;
  text-align: center;
}
.resource-table-auto { width: 100%; table-layout: auto; }
.resource-table-auto th, .resource-table-auto td { white-space: nowrap; }

/* Nav-main (trang con dùng nav đơn giản) */
.nav-main { background: var(--bg-card); border-bottom: 1px solid var(--border); padding: 0.75rem 1.5rem; }
.nav-main .logo { display: inline-flex; align-items: center; font-weight: 600; font-size: 1.1rem; color: var(--text-primary); text-decoration: none; }
.nav-main .logo:hover { color: var(--text-primary); }
.nav-main .logo span { color: var(--accent-cpp); }

.footer { margin-top: 4rem; padding: 2rem; border-top: 1px solid var(--border); text-align: center; color: var(--text-muted); font-size: 0.9rem; }

@media (max-width: 768px) {
  .hero { padding: 2rem 1rem; }
  .hero-stats { gap: 1.5rem; }
  .container { padding: 1rem; }
  .cards-grid { grid-template-columns: 1fr; }
}

pre, code { font-family: var(--font-sans); background: var(--bg-tertiary); padding: 0.2rem 0.4rem; border-radius: 4px; font-size: 0.9em; }
pre { padding: 1rem; overflow-x: auto; margin: 1rem 0; border: 1px solid var(--border); }

.loading { text-align: center; padding: 3rem; color: var(--text-muted); }
.loading::after {
  content: '';
  display: inline-block;
  width: 24px; height: 24px;
  border: 2px solid var(--border);
  border-top-color: var(--accent-cpp);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-left: 0.5rem;
  vertical-align: middle;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ===== Floating Contact (như ảnh: Phone, Gmail, Zalo, Facebook) ===== */
.floating-contact {
  position: fixed;
  top: 50%;
  right: 20px;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 12px;
  z-index: 998;
  pointer-events: none;
}

.floating-contact .floating-contact-btn {
  pointer-events: auto;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  text-decoration: none;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.floating-contact .floating-contact-btn:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 16px rgba(0,0,0,0.25);
  text-decoration: none;
}

.floating-contact-phone {
  background: #e53935;
  color: #fff;
}

.floating-contact-phone i { font-size: 1.35rem; }

.floating-contact-email {
  background: #fff;
  border: 2px solid #dc3545;
}

.floating-contact-email img { width: 24px; height: 24px; object-fit: contain; display: block; }

.floating-contact-zalo {
  background: #fff;
  border: 2px solid #0068ff;
}

.floating-contact-zalo img { width: 24px; height: 24px; object-fit: contain; display: block; }

.floating-contact-facebook {
  background: #fff;
  border: 2px solid #9bc4f5;
}

.floating-contact-facebook img,
.floating-contact-facebook i { width: 24px; height: 24px; object-fit: contain; display: block; font-size: 1.3rem; color: #fff; }
.floating-contact-facebook i {
  background: #1877F2;
  border-radius: 50%;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  margin: 0 auto;
}

/* Scroll progress */
.scroll-progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 4px;
  width: 0%;
  background: var(--accent-cpp);
  z-index: 1001;
  transition: width 0.08s ease-out;
  pointer-events: none;
}

/* Back to top */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 90px;
  width: 50px;
  height: 50px;
  background: var(--accent-cpp);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 1.25rem;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  transition: transform 0.2s, opacity 0.2s;
  z-index: 997;
  display: flex;
  align-items: center;
  justify-content: center;
}

.back-to-top:hover { transform: scale(1.08); opacity: 0.9; }
.back-to-top.hidden { opacity: 0; pointer-events: none; }

@media (max-width: 768px) {
  .floating-contact { right: 12px; gap: 8px; }
  .floating-contact .floating-contact-btn { width: 46px; height: 46px; }
  .back-to-top { right: 70px; bottom: 20px; width: 44px; height: 44px; }
}

/* ===== Share Modal (giống hình 4 / URL) ===== */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  z-index: 999999;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  overflow-y: auto;
  backdrop-filter: blur(5px);
}
.modal.active { display: flex; }
.modal-content {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 600px;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-strong);
}
.modal-medium { max-width: 600px; }
.modal-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.modal-header h2 { font-size: 1.25rem; font-weight: 600; margin: 0; }
.modal-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.25rem;
}
.modal-close:hover { color: var(--text-primary); }
.modal-body { padding: 1.25rem; overflow-y: auto; }
.share-content { display: flex; flex-direction: column; gap: 1.25rem; }
.share-preview {
  background: var(--bg-secondary);
  border-radius: var(--radius);
  padding: 1rem;
  border: 1px solid var(--border);
}
.share-preview-info h3 { font-size: 0.95rem; margin-bottom: 0.25rem; }
.share-preview-info p { font-size: 0.875rem; color: var(--text-secondary); line-height: 1.5; }
.share-platforms {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 0.75rem;
}
.share-platform-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
  padding: 0.75rem;
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.2s ease;
  color: var(--text-primary);
  font-size: 0.8rem;
  font-weight: 500;
  min-height: 85px;
}
.share-platform-btn:hover {
  border-color: var(--platform-color, var(--accent-cpp));
  background: var(--bg-secondary);
  transform: translateY(-2px);
}
.share-platform-btn i { font-size: 1.5rem; color: var(--platform-color, var(--accent-cpp)); }
.share-platform-btn .share-btn-icon { width: 28px; height: 28px; object-fit: contain; }
.share-link-section label { font-weight: 600; font-size: 0.875rem; display: block; margin-bottom: 0.35rem; }
.share-link-input {
  display: flex;
  gap: 0.5rem;
}
.share-link-input input {
  flex: 1;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-primary);
  color: var(--text-primary);
  font-size: 0.875rem;
}
.btn-copy-link {
  padding: 0.5rem 1rem;
  background: var(--accent-cpp);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 500;
  white-space: nowrap;
}
.btn-copy-link:hover { opacity: 0.9; }

/* === Language Detail Modal (Learning Section) === */
.lang-detail-modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 10000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  overflow-y: auto;
}
.lang-detail-modal > div {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  max-width: 800px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  position: relative;
  margin: auto;
  box-shadow: var(--shadow-strong);
}
.lang-detail-modal .close-modal {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background 0.2s;
}
.lang-detail-modal .close-modal:hover {
  background: var(--bg-tertiary);
}
.lang-detail-modal .lang-modal-title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  color: var(--text-primary);
  font-size: 1.75rem;
}
.lang-detail-modal .lang-modal-title i {
  color: var(--accent-cpp);
}
.lang-detail-modal .lang-modal-desc {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}
.lang-detail-modal .lang-modal-btns {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}
.lang-detail-modal .lang-modal-btn {
  flex: 1;
  min-width: 180px;
  padding: 0.75rem;
  border-radius: var(--radius);
  text-decoration: none;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: all 0.2s;
  font-size: 1rem;
  font-weight: 500;
  border: none;
  cursor: pointer;
}
.lang-detail-modal .lang-modal-btn-official {
  background: #1e3a5f;
  color: #fff;
}
.lang-detail-modal .lang-modal-btn-official:hover {
  background: #2d4a6f;
}
.lang-detail-modal .lang-modal-btn-learn {
  background: #3b82f6;
  color: #fff;
}
.lang-detail-modal .lang-modal-btn-learn:hover {
  background: #2563eb;
}
.lang-detail-modal .lang-modal-stats {
  background: var(--bg-secondary);
  padding: 1rem;
  border-radius: var(--radius);
  margin-bottom: 1.5rem;
}
.lang-detail-modal .lang-modal-stats h3,
.lang-detail-modal .lang-modal-path h3 {
  margin-bottom: 0.75rem;
  color: var(--text-primary);
  font-size: 1.2rem;
}
.lang-detail-modal .lang-modal-stats-inner {
  display: flex;
  gap: 2rem;
  flex-wrap: wrap;
}
.lang-detail-modal .lang-modal-stats-inner span {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-secondary);
}
.lang-detail-modal .lang-modal-path-inner {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.lang-detail-modal .lang-modal-path-item {
  padding: 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all 0.2s;
}
.lang-detail-modal .lang-modal-path-item:hover {
  border-color: var(--accent-cpp);
  box-shadow: 0 2px 8px rgba(14, 165, 233, 0.15);
}
.lang-detail-modal .lang-modal-path-head {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
  flex-wrap: wrap;
}
.lang-detail-modal .lang-modal-path-num {
  background: var(--accent-cpp);
  color: #fff;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  font-weight: bold;
  flex-shrink: 0;
}
.lang-detail-modal .lang-modal-path-item p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 0;
  line-height: 1.6;
}
@media (max-width: 768px) {
  .lang-detail-modal {
    padding: 0.5rem;
    align-items: flex-start;
    padding-top: 1rem;
  }
  .lang-detail-modal > div {
    padding: 1rem;
    max-height: calc(100vh - 2rem);
  }
  .lang-detail-modal .lang-modal-title { font-size: 1.5rem; }
  .lang-detail-modal .lang-modal-btns { flex-direction: column; }
  .lang-detail-modal .lang-modal-btn { min-width: auto; width: 100%; }
  .lang-detail-modal .lang-modal-stats-inner { flex-direction: column; gap: 0.5rem; }
}