:root, [data-theme="midnight"] {
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: rgba(30, 41, 59, 0.7);
  --bg-card-hover: rgba(51, 65, 85, 0.85);
  --border-color: rgba(255, 255, 255, 0.1);
  --border-hover: rgba(56, 189, 248, 0.4);
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-primary: #38bdf8;
  --accent-hover: #0ea5e9;
  --accent-glow: rgba(56, 189, 248, 0.15);
  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.12);
  --warning: #f59e0b;
  --tag-empower: #8b5cf6;
  --tag-empower-bg: rgba(139, 92, 246, 0.15);
  --tag-esp: #0284c7;
  --tag-esp-bg: rgba(2, 132, 199, 0.15);
  --tag-grammar: #10b981;
  --tag-grammar-bg: rgba(16, 185, 129, 0.15);
  --tag-listening: #f59e0b;
  --tag-listening-bg: rgba(245, 158, 11, 0.15);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-card: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  --bg-grad-1: rgba(56, 189, 248, 0.08);
  --bg-grad-2: rgba(139, 92, 246, 0.08);
}

/* THEME 2: WARM PARCHMENT / EYE-COMFORT (Soft, Anti-Glare Warm Light) */
[data-theme="warm"] {
  --bg-primary: #f6f2ea;
  --bg-secondary: #eee8dc;
  --bg-card: rgba(255, 253, 249, 0.85);
  --bg-card-hover: #ffffff;
  --border-color: rgba(120, 100, 80, 0.14);
  --border-hover: rgba(180, 83, 9, 0.4);
  --text-primary: #2d261e;
  --text-secondary: #5c5245;
  --text-muted: #8c7e6d;
  --accent-primary: #0f766e;
  --accent-hover: #0d655e;
  --accent-glow: rgba(15, 118, 110, 0.15);
  --success: #059669;
  --success-bg: rgba(5, 150, 105, 0.12);
  --warning: #d97706;
  --tag-empower: #6d28d9;
  --tag-empower-bg: rgba(109, 40, 217, 0.12);
  --tag-esp: #0f766e;
  --tag-esp-bg: rgba(15, 118, 110, 0.12);
  --tag-grammar: #059669;
  --tag-grammar-bg: rgba(5, 150, 105, 0.12);
  --tag-listening: #b45309;
  --tag-listening-bg: rgba(180, 83, 9, 0.12);
  --shadow-card: 0 10px 28px -4px rgba(60, 40, 20, 0.07), 0 0 0 1px rgba(120, 100, 80, 0.08);
  --bg-grad-1: rgba(217, 119, 6, 0.06);
  --bg-grad-2: rgba(15, 118, 110, 0.06);
}

/* THEME 3: EMERALD FOREST (Calm Green Dark) */
[data-theme="emerald"] {
  --bg-primary: #06281e;
  --bg-secondary: #0b3b2d;
  --bg-card: rgba(11, 59, 45, 0.75);
  --bg-card-hover: rgba(16, 78, 60, 0.9);
  --border-color: rgba(52, 211, 153, 0.15);
  --border-hover: rgba(52, 211, 153, 0.45);
  --text-primary: #f0fdf4;
  --text-secondary: #a7f3d0;
  --text-muted: #6ee7b7;
  --accent-primary: #34d399;
  --accent-hover: #10b981;
  --accent-glow: rgba(52, 211, 153, 0.2);
  --success: #34d399;
  --success-bg: rgba(52, 211, 153, 0.15);
  --shadow-card: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
  --bg-grad-1: rgba(52, 211, 153, 0.08);
  --bg-grad-2: rgba(6, 95, 70, 0.12);
}

/* THEME 4: ESPRESSO AMBER (Warm Cozy Dark) */
[data-theme="amber"] {
  --bg-primary: #1c1917;
  --bg-secondary: #292524;
  --bg-card: rgba(41, 37, 36, 0.8);
  --bg-card-hover: rgba(68, 64, 60, 0.9);
  --border-color: rgba(251, 191, 36, 0.15);
  --border-hover: rgba(251, 191, 36, 0.45);
  --text-primary: #fef3c7;
  --text-secondary: #d6d3d1;
  --text-muted: #a8a29e;
  --accent-primary: #fbbf24;
  --accent-hover: #f59e0b;
  --accent-glow: rgba(251, 191, 36, 0.2);
  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.12);
  --shadow-card: 0 8px 32px 0 rgba(0, 0, 0, 0.45);
  --bg-grad-1: rgba(251, 191, 36, 0.07);
  --bg-grad-2: rgba(180, 83, 9, 0.07);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  background-image: 
    radial-gradient(at 0% 0%, var(--bg-grad-1) 0px, transparent 50%),
    radial-gradient(at 100% 100%, var(--bg-grad-2) 0px, transparent 50%);
  background-attachment: fixed;
  display: flex;
  flex-direction: column;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Container */
.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

/* Header & Navigation */
.portal-header {
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  position: sticky;
  top: 0;
  z-index: 50;
  transition: var(--transition);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 74px;
}

.brand-badge {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-icon {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}

.brand-icon img {
  width: 100%;
  height: 100%;
}

.brand-title {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.brand-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Theme Dots Swatches */
.theme-swatches-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 4px 8px;
  border-radius: 9999px;
}

.theme-swatches-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-right: 2px;
  display: none;
}

@media (min-width: 600px) {
  .theme-swatches-label {
    display: inline-block;
  }
}

.theme-dot {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.2s ease;
  position: relative;
  outline: none;
}

.theme-dot:hover {
  transform: scale(1.25);
}

.theme-dot.active {
  border-color: var(--text-primary);
  box-shadow: 0 0 0 2px var(--bg-secondary), 0 0 8px rgba(0,0,0,0.3);
  transform: scale(1.15);
}

.dot-warm {
  background: linear-gradient(135deg, #f6f2ea 50%, #0f766e 50%);
  border: 1px solid rgba(0,0,0,0.15);
}

.dot-midnight {
  background: linear-gradient(135deg, #0f172a 50%, #38bdf8 50%);
}

.dot-emerald {
  background: linear-gradient(135deg, #06281e 50%, #34d399 50%);
}

.dot-amber {
  background: linear-gradient(135deg, #1c1917 50%, #fbbf24 50%);
}

/* Privacy Guarantee Banner */
.privacy-banner {
  background: var(--success-bg);
  border-bottom: 1px solid rgba(16, 185, 129, 0.2);
  padding: 0.75rem 0;
  font-size: 0.875rem;
  color: var(--success);
}

.privacy-banner-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  text-align: center;
  font-weight: 600;
}

.privacy-banner svg {
  flex-shrink: 0;
}

/* Hero Section */
.hero {
  padding: 3.5rem 0 2rem;
  text-align: center;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  background: var(--accent-glow);
  border: 1px solid var(--accent-primary);
  border-radius: 9999px;
  color: var(--accent-primary);
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
}

.hero h1 {
  font-size: 2.75rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.hero p {
  color: var(--text-secondary);
  font-size: 1.15rem;
  max-width: 680px;
  margin: 0 auto 2rem;
}

/* Search and Filters */
.controls-wrap {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  margin-bottom: 2.5rem;
}

.search-box {
  position: relative;
  max-width: 600px;
  width: 100%;
  margin: 0 auto;
}

.search-box input {
  width: 100%;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem 1rem 3rem;
  color: var(--text-primary);
  font-size: 1rem;
  font-family: inherit;
  outline: none;
  transition: var(--transition);
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.search-box input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-box svg {
  position: absolute;
  left: 1.1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

/* Category Filter Tabs */
.filter-tabs {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
}

.filter-btn {
  background: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  padding: 0.6rem 1.2rem;
  border-radius: 9999px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.filter-btn:hover {
  color: var(--text-primary);
  border-color: var(--accent-primary);
}

.filter-btn.active {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 14px var(--accent-glow);
}

/* Category Sections */
.category-group {
  margin-bottom: 3.5rem;
}

.category-group.hidden {
  display: none;
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.section-title {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: 700;
}

.section-badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 9999px;
  text-transform: uppercase;
}

/* Grid of Cards */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.lesson-card {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.lesson-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-primary), transparent);
  opacity: 0;
  transition: var(--transition);
}

.lesson-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-card);
}

.lesson-card:hover::before {
  opacity: 1;
}

.card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.card-tag {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 6px;
  letter-spacing: 0.02em;
}

.tag-empower { background: var(--tag-empower-bg); color: var(--tag-empower); }
.tag-esp { background: var(--tag-esp-bg); color: var(--tag-esp); }
.tag-grammar { background: var(--tag-grammar-bg); color: var(--tag-grammar); }
.tag-listening { background: var(--tag-listening-bg); color: var(--tag-listening); }

.card-level {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
}

.card-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  line-height: 1.35;
}

.card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

.card-meta-item {
  display: flex;
  align-items: center;
  gap: 4px;
}

.card-action-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 0.8rem 1rem;
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
}

.card-action-btn:hover {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 12px var(--accent-glow);
}

/* Empty search state */
.empty-state {
  text-align: center;
  padding: 4rem 1rem;
  display: none;
}

.empty-state.active {
  display: block;
}

.empty-state svg {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.empty-state h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.empty-state p {
  color: var(--text-secondary);
}

/* Footer */
.portal-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-color);
  background: var(--bg-card);
  padding: 2.5rem 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  text-align: center;
}

.footer-privacy-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--success-bg);
  color: var(--success);
  padding: 4px 12px;
  border-radius: 9999px;
  font-weight: 600;
}

/* Hierarchical Curriculum Explorer & Sub-Book Navigation */
.sub-book-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 8px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 9999px;
  width: fit-content;
}

.sub-book-label {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-right: 2px;
  padding-left: 4px;
}

.sub-book-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-secondary);
  padding: 5px 14px;
  border-radius: 9999px;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.sub-book-btn:hover {
  color: var(--text-primary);
  background: var(--bg-card-hover);
}

.sub-book-btn.active {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 12px var(--accent-glow);
}

/* Unit Sub-Navigation Bar & Quick-Filter Boxes */
.unit-nav-bar {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin: 1.25rem 0 1.75rem 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.04);
  transition: var(--transition);
}

.unit-nav-bar:hover {
  border-color: var(--border-hover);
}

.unit-nav-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.85rem;
  gap: 12px;
  flex-wrap: wrap;
}

.unit-nav-title-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
}

.unit-nav-icon {
  color: var(--accent-primary);
  flex-shrink: 0;
}

.unit-nav-title {
  font-size: 0.82rem;
  font-weight: 800;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.unit-count-badge {
  font-size: 0.78rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 9999px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--accent-primary);
  letter-spacing: 0.02em;
}

.unit-chips-container {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.unit-chip-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 7px 14px;
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
  min-height: 38px;
  line-height: 1;
}

.unit-chip-btn:hover {
  color: var(--text-primary);
  border-color: var(--accent-primary);
  background: var(--bg-card-hover);
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
}

.unit-chip-btn.active {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 14px var(--accent-glow);
  transform: translateY(-1px);
}

.chip-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.8;
}

.chip-special {
  border-color: rgba(139, 92, 246, 0.35);
}

.chip-special:hover {
  border-color: var(--tag-empower);
}

.chip-special.active {
  background: var(--tag-empower);
  border-color: var(--tag-empower);
}

/* Card Animation */
@keyframes cardFadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.lesson-card.visible-animated {
  animation: cardFadeIn 0.22s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Hierarchical Unit Card */
.unit-card-hierarchical {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-card);
}

.unit-card-hierarchical:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}

.unit-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: 0.75rem;
}

.unit-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
}

.unit-card-subtitle {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
}

/* 5 Sub-Module Action Pills */
.unit-submodules-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 8px;
  margin-top: 1rem;
}

.submod-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--border-color);
  background: var(--bg-secondary);
  color: var(--text-primary);
  transition: var(--transition);
  text-align: center;
}

.submod-pill:hover:not(.faded) {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 10px var(--accent-glow);
}

.submod-pill.faded {
  opacity: 0.45;
  cursor: not-allowed;
  background: transparent;
  border-style: dashed;
  color: var(--text-muted);
}

.submod-pill.faded:hover {
  opacity: 0.6;
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }
  .cards-grid {
    grid-template-columns: 1fr;
  }
  .unit-submodules-grid {
    grid-template-columns: 1fr 1fr;
  }
  .filter-tabs {
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 6px;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
  }
  .filter-btn {
    white-space: nowrap;
  }
  .sub-book-nav {
    width: 100%;
    overflow-x: auto;
    flex-wrap: nowrap;
  }
}