/* ═══════════════════════════════════════════════
   RAZ English Learning — Storybook World Theme
   Child-friendly design for ages 5-8
   ═══════════════════════════════════════════════ */

/* ── Google Fonts loaded in HTML ── */

/* ── CSS Variables ── */
:root {
  /* Colors — warm storybook palette */
  --c-bg: #FFF8F0;
  --c-bg-warm: #FFF1E6;
  --c-bg-cool: #F0F7FF;
  --c-card: #FFFFFF;
  --c-primary: #FF6B6B;
  --c-primary-dark: #E85555;
  --c-primary-light: #FFB4B4;
  --c-secondary: #4ECDC4;
  --c-secondary-dark: #3BB8B0;
  --c-secondary-light: #A8EDE8;
  --c-accent: #FFE66D;
  --c-accent-dark: #FFD93D;
  --c-success: #51CF66;
  --c-success-light: #D3F9D8;
  --c-warning: #FFA94D;
  --c-danger: #FF6B6B;
  --c-purple: #B197FC;
  --c-pink: #F783AC;

  /* Text */
  --c-text: #2B2D42;
  --c-text-light: #6C757D;
  --c-text-muted: #ADB5BD;
  --c-text-white: #FFFFFF;

  /* Borders & shadows */
  --c-border: #E9ECEF;
  --c-border-light: #F1F3F5;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
  --shadow-card: 0 3px 12px rgba(0,0,0,0.07);
  --shadow-btn: 0 4px 0 rgba(0,0,0,0.1);
  --shadow-inset: inset 0 2px 4px rgba(0,0,0,0.05);

  /* Typography */
  --font-display: 'Fredoka', 'Comic Sans MS', cursive;
  --font-body: 'Nunito', 'Segoe UI', sans-serif;
  --fs-hero: 2rem;
  --fs-h1: 1.6rem;
  --fs-h2: 1.3rem;
  --fs-h3: 1.1rem;
  --fs-body: 1rem;
  --fs-small: 0.85rem;
  --fs-xs: 0.75rem;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Borders */
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 100px;

  /* Layout */
  --nav-height: 64px;
  --sidebar-width: 220px;
  --header-height: 56px;
  --max-width: 480px;
  --content-max-width: 900px;
}

/* ── Reset & Base ── */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-body);
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.5;
  overflow-x: hidden;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* Subtle paper texture via gradient */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(255,107,107,0.03) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(78,205,196,0.03) 0%, transparent 50%),
    radial-gradient(ellipse at 40% 80%, rgba(255,230,109,0.04) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

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

button {
  font-family: var(--font-body);
  cursor: pointer;
  border: none;
  background: none;
  font-size: inherit;
  color: inherit;
  -webkit-tap-highlight-color: transparent;
}

a { color: var(--c-primary); text-decoration: none; }

/* ── App Container ── */
#app {
  position: relative;
  max-width: var(--max-width);
  margin: 0 auto;
  min-height: 100vh;
  padding-bottom: calc(var(--nav-height) + 12px);
  z-index: 1;
  transition: margin-left 0.3s ease, max-width 0.3s ease;
}

/* ── Pages ── */
.page {
  display: none;
  padding: var(--space-md);
  padding-top: var(--space-lg);
  animation: pageFadeIn 0.3s ease;
  min-height: calc(100vh - var(--nav-height));
}

.page.active {
  display: block;
}

.page.full-page {
  padding: 0;
  position: fixed;
  inset: 0;
  z-index: 100;
  background: var(--c-bg);
  max-width: none;
  overflow-y: auto;
  display: none;
  animation: pageSlideIn 0.35s cubic-bezier(0.22, 1, 0.36, 1);
}

.page.full-page.active {
  display: flex;
  flex-direction: column;
}

/* ── Navigation (mobile: bottom bar / desktop: sidebar) ── */
.app-nav {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: var(--max-width);
  height: var(--nav-height);
  background: var(--c-card);
  border-top: 1px solid var(--c-border-light);
  z-index: 50;
  box-shadow: 0 -2px 12px rgba(0,0,0,0.04);
  padding-bottom: env(safe-area-inset-bottom, 0);
  transition: transform 0.3s ease;
}

.app-nav.nav-hidden {
  transform: translateX(-50%) translateY(100%);
}

.nav-brand {
  display: none; /* hidden on mobile */
}

.nav-items {
  display: flex;
  align-items: center;
  justify-content: space-around;
  height: 100%;
}

/* Mobile: hide Words and Listen from bottom bar (accessible via More/Stats) */
.nav-item[data-page="words"],
.nav-item[data-page="listen"] {
  display: none;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 6px 12px;
  border-radius: var(--radius-md);
  transition: all 0.2s ease;
  min-width: 56px;
  position: relative;
}

.nav-item .nav-icon {
  font-size: 1.5rem;
  line-height: 1;
  transition: transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.nav-item .nav-label {
  font-size: var(--fs-xs);
  font-weight: 600;
  color: var(--c-text-muted);
  transition: color 0.2s ease;
}

.nav-item.active .nav-icon {
  transform: scale(1.15);
}

.nav-item.active .nav-label {
  color: var(--c-primary);
  font-weight: 700;
}

.nav-item.active::after {
  content: '';
  position: absolute;
  top: -1px;
  left: 50%;
  transform: translateX(-50%);
  width: 28px;
  height: 3px;
  background: var(--c-primary);
  border-radius: 0 0 3px 3px;
}

.nav-item:active .nav-icon {
  transform: scale(0.9);
}

.nav-badge {
  position: absolute;
  top: 2px;
  right: 4px;
  background: var(--c-primary);
  color: white;
  font-size: 10px;
  font-weight: 700;
  min-width: 18px;
  height: 18px;
  border-radius: 9px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 4px;
}

/* ── Page Header ── */
.page-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
}

.page-title {
  font-family: var(--font-display);
  font-size: var(--fs-h1);
  font-weight: 600;
  color: var(--c-text);
}

.page-subtitle {
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

.back-btn {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--c-card);
  box-shadow: var(--shadow-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  transition: all 0.15s ease;
  flex-shrink: 0;
}

.back-btn:active {
  transform: scale(0.9);
}

/* ── Cards ── */
.card {
  background: var(--c-card);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:active {
  transform: scale(0.98);
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 12px 24px;
  border-radius: var(--radius-full);
  font-family: var(--font-display);
  font-size: var(--fs-body);
  font-weight: 500;
  transition: all 0.15s ease;
  position: relative;
  user-select: none;
}

.btn:active {
  transform: translateY(2px);
}

.btn-primary {
  background: var(--c-primary);
  color: white;
  box-shadow: 0 4px 0 var(--c-primary-dark), var(--shadow-sm);
}

.btn-primary:active {
  box-shadow: 0 1px 0 var(--c-primary-dark);
  transform: translateY(3px);
}

.btn-secondary {
  background: var(--c-secondary);
  color: white;
  box-shadow: 0 4px 0 var(--c-secondary-dark), var(--shadow-sm);
}

.btn-secondary:active {
  box-shadow: 0 1px 0 var(--c-secondary-dark);
  transform: translateY(3px);
}

.btn-accent {
  background: var(--c-accent);
  color: var(--c-text);
  box-shadow: 0 4px 0 var(--c-accent-dark), var(--shadow-sm);
}

.btn-ghost {
  background: transparent;
  color: var(--c-text-light);
  padding: 8px 16px;
}

.btn-ghost:active {
  background: var(--c-border-light);
}

.btn-icon {
  width: 48px;
  height: 48px;
  padding: 0;
  border-radius: var(--radius-full);
  background: var(--c-card);
  box-shadow: var(--shadow-sm);
  font-size: 1.4rem;
}

.btn-icon:active {
  transform: scale(0.9);
  box-shadow: none;
}

.btn-large {
  padding: 16px 32px;
  font-size: 1.15rem;
}

.btn-block {
  width: 100%;
}

/* Emoji rating buttons */
.btn-emoji {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 12px 8px;
  border-radius: var(--radius-lg);
  background: var(--c-card);
  box-shadow: var(--shadow-card);
  min-width: 72px;
  transition: all 0.15s ease;
}

.btn-emoji:active {
  transform: scale(0.92);
  box-shadow: var(--shadow-sm);
}

.btn-emoji .emoji {
  font-size: 2rem;
}

.btn-emoji .label {
  font-size: var(--fs-xs);
  font-weight: 600;
  color: var(--c-text-light);
}

.btn-emoji[data-rating="0"] { border: 2px solid transparent; }
.btn-emoji[data-rating="0"]:active { border-color: var(--c-danger); background: #FFF5F5; }
.btn-emoji[data-rating="1"] { border: 2px solid transparent; }
.btn-emoji[data-rating="1"]:active { border-color: var(--c-warning); background: #FFF9F0; }
.btn-emoji[data-rating="2"] { border: 2px solid transparent; }
.btn-emoji[data-rating="2"]:active { border-color: var(--c-success); background: #F0FFF4; }
.btn-emoji[data-rating="3"] { border: 2px solid transparent; }
.btn-emoji[data-rating="3"]:active { border-color: var(--c-accent-dark); background: #FFFEF0; }

/* ── Progress Bar ── */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--c-border-light);
  border-radius: 4px;
  overflow: hidden;
}

.progress-bar.thick {
  height: 12px;
}

.progress-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.4s cubic-bezier(0.22, 1, 0.36, 1);
  background: linear-gradient(90deg, var(--c-secondary), var(--c-secondary-dark));
}

.progress-fill.primary { background: linear-gradient(90deg, var(--c-primary-light), var(--c-primary)); }
.progress-fill.success { background: linear-gradient(90deg, #73D677, var(--c-success)); }
.progress-fill.accent { background: linear-gradient(90deg, var(--c-accent), var(--c-accent-dark)); }

/* ── Badges / Tags ── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  font-weight: 700;
}

.badge-new { background: #E8F5FF; color: #3B82F6; }
.badge-learning { background: #FFF3E0; color: #F59E0B; }
.badge-reviewing { background: #F3E8FF; color: #8B5CF6; }
.badge-mastered { background: var(--c-success-light); color: #2F9E44; }
.badge-level { background: var(--c-primary-light); color: var(--c-primary-dark); }

/* ── Stat Cards ── */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-sm);
}

.stat-card {
  background: var(--c-card);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  text-align: center;
  box-shadow: var(--shadow-sm);
}

.stat-card .stat-value {
  font-family: var(--font-display);
  font-size: var(--fs-h1);
  font-weight: 600;
  color: var(--c-primary);
  line-height: 1.2;
}

.stat-card .stat-label {
  font-size: var(--fs-xs);
  color: var(--c-text-light);
  margin-top: 2px;
}

.stat-card.highlight {
  background: linear-gradient(135deg, var(--c-primary), #FF8E8E);
  color: white;
}

.stat-card.highlight .stat-value {
  color: white;
}

.stat-card.highlight .stat-label {
  color: rgba(255,255,255,0.85);
}

/* ═══ HOME PAGE ═══ */
.home-greeting {
  font-family: var(--font-display);
  font-size: var(--fs-hero);
  margin-bottom: var(--space-xs);
  line-height: 1.3;
}

.home-date {
  font-size: var(--fs-small);
  color: var(--c-text-light);
  margin-bottom: var(--space-lg);
}

.streak-display {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  background: linear-gradient(135deg, #FF6B6B, #FFA94D);
  color: white;
  border-radius: var(--radius-lg);
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-lg);
  box-shadow: var(--shadow-md);
}

.streak-display .streak-fire {
  font-size: 2.2rem;
}

.streak-display .streak-count {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 600;
}

.streak-display .streak-label {
  font-size: var(--fs-small);
  opacity: 0.9;
}

.today-plan {
  margin-top: var(--space-lg);
}

.plan-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  background: var(--c-card);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-sm);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: transform 0.15s ease;
}

.plan-item.done {
  background: #F4FFF7;
  border: 2px solid #BEE8C8;
}

.plan-item:active {
  transform: scale(0.98);
}

.plan-item .plan-icon {
  font-size: 1.8rem;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.plan-item .plan-icon.review { background: #FFE8E8; }
.plan-item .plan-icon.book { background: #E8F5FF; }
.plan-item .plan-icon.game { background: #F0FFF4; }
.plan-item .plan-icon.listen { background: #FFF3E0; }

.plan-item .plan-info {
  flex: 1;
}

.plan-item .plan-title {
  font-family: var(--font-display);
  font-size: var(--fs-body);
  font-weight: 500;
}

.plan-item .plan-desc {
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

.plan-item .plan-arrow {
  color: var(--c-text-muted);
  font-size: 1.2rem;
}

.plan-item.done .plan-arrow {
  color: var(--c-success);
  font-weight: 800;
}

/* Recent achievements */
.recent-achievements {
  margin-top: var(--space-lg);
}

.section-title {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.achievement-mini {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background: var(--c-card);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-sm);
  font-size: var(--fs-small);
  margin-right: var(--space-sm);
  margin-bottom: var(--space-sm);
}

.achievement-mini .achievement-icon {
  font-size: 1.3rem;
}

/* ═══ BOOKSHELF ═══ */
.filter-bar {
  display: flex;
  gap: var(--space-sm);
  overflow-x: auto;
  padding-bottom: var(--space-sm);
  margin-bottom: var(--space-md);
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.filter-bar::-webkit-scrollbar { display: none; }

.filter-chip {
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: var(--c-card);
  font-size: var(--fs-small);
  font-weight: 600;
  white-space: nowrap;
  box-shadow: var(--shadow-sm);
  transition: all 0.15s ease;
  border: 2px solid transparent;
}

.filter-chip.active {
  background: var(--c-primary);
  color: white;
  box-shadow: 0 2px 8px rgba(255,107,107,0.3);
}

.filter-chip:active {
  transform: scale(0.95);
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
}

.book-card {
  background: var(--c-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease;
  cursor: pointer;
  position: relative;
}

.book-card:active {
  transform: scale(0.96);
}

.book-cover {
  width: 100%;
  aspect-ratio: 3/4;
  object-fit: cover;
  background: var(--c-bg-warm);
}

.book-cover.landscape {
  aspect-ratio: 4/3;
}

.book-info {
  padding: var(--space-sm);
}

.book-title {
  font-family: var(--font-display);
  font-size: var(--fs-xs);
  font-weight: 500;
  line-height: 1.3;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.book-status-dot {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  border: 2px solid white;
  box-shadow: var(--shadow-sm);
}

.book-status-dot.new { background: var(--c-text-muted); }
.book-status-dot.previewed { background: var(--c-warning); }
.book-status-dot.read { background: var(--c-secondary); }
.book-status-dot.mastered { background: var(--c-success); }

/* Book detail modal */
.book-modal {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: var(--max-width);
  background: var(--c-card);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
  padding: var(--space-lg);
  box-shadow: var(--shadow-lg);
  z-index: 200;
  animation: slideUp 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}

.book-modal-header {
  display: flex;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.book-modal-cover {
  width: 80px;
  height: 100px;
  object-fit: cover;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
}

.book-modal-info { flex: 1; }

.book-modal-title {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  margin-bottom: 4px;
}

.book-modal-meta {
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

.book-modal-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.book-modal-actions .btn {
  justify-content: flex-start;
  padding: 14px 20px;
  border-radius: var(--radius-lg);
  font-family: var(--font-body);
  font-weight: 600;
}

/* ═══ READER ═══ */
.reader-container {
  display: flex;
  flex-direction: column;
  height: 100%;
  background: var(--c-bg);
}

.reader-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md);
  flex-shrink: 0;
}

.reader-header .reader-title {
  flex: 1;
  font-family: var(--font-display);
  font-size: var(--fs-body);
  font-weight: 500;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.reader-progress {
  padding: 0 var(--space-md);
  flex-shrink: 0;
}

.reader-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
  overflow-y: auto;
  gap: var(--space-md);
}

.reader-image-wrapper {
  width: 100%;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: white;
  display: flex;
  align-items: center;
  justify-content: center;
}

.reader-image {
  max-width: 100%;
  max-height: 60vh;
  width: auto;
  height: auto;
  display: block;
}

.reader-text {
  font-family: var(--font-display);
  font-size: 1.5rem;
  text-align: center;
  padding: var(--space-md);
  line-height: 1.6;
  color: var(--c-text);
}

.reader-text .word {
  display: inline-block;
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

.reader-text .word:active,
.reader-text .word.highlight {
  background: var(--c-accent);
  transform: scale(1.15);
}

.reader-text.hidden {
  visibility: hidden;
}

.reader-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  padding: var(--space-md);
  flex-shrink: 0;
}

.reader-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-md) var(--space-md);
  flex-shrink: 0;
}

.reader-page-num {
  font-family: var(--font-display);
  font-size: var(--fs-body);
  color: var(--c-text-light);
}

/* Preview mode word cards */
.preview-card {
  text-align: center;
  padding: var(--space-lg);
}

.preview-word {
  font-family: var(--font-display);
  font-size: 2.5rem;
  color: var(--c-primary);
  margin: var(--space-md) 0;
  animation: wordBounce 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.preview-sentence {
  font-size: var(--fs-h3);
  color: var(--c-text-light);
  font-style: italic;
}

.preview-source {
  font-size: var(--fs-small);
  color: var(--c-text-muted);
  margin-top: var(--space-sm);
}

/* Text mode toggles */
.mode-toggles {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  flex-wrap: wrap;
}

.mode-toggle {
  padding: 6px 14px;
  border-radius: var(--radius-full);
  background: var(--c-border-light);
  font-size: var(--fs-small);
  font-weight: 600;
  transition: all 0.15s ease;
}

.mode-toggle.active {
  background: var(--c-secondary);
  color: white;
}

/* ═══ FLASHCARD REVIEW ═══ */
.review-container {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.review-header {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md);
  flex-shrink: 0;
}

.review-count {
  font-family: var(--font-display);
  font-size: var(--fs-small);
  color: var(--c-text-light);
  text-align: center;
  flex: 1;
}

.review-body {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
}

/* Flashcard */
.flashcard {
  width: 100%;
  max-width: 360px;
  perspective: 1000px;
  cursor: pointer;
}

.flashcard-inner {
  position: relative;
  min-height: 420px;
  transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
  transform-style: preserve-3d;
}

.flashcard.flipped .flashcard-inner {
  transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  background: var(--c-card);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  overflow-y: auto;
}

.flashcard-back {
  transform: rotateY(180deg);
}

.flashcard-image {
  width: 100%;
  max-height: 200px;
  object-fit: contain;
  border-radius: var(--radius-md);
  margin-bottom: var(--space-md);
}

.flashcard-word {
  font-family: var(--font-display);
  font-size: 2.2rem;
  color: var(--c-primary);
  text-align: center;
}

.flashcard-sentence {
  font-size: var(--fs-body);
  color: var(--c-text-light);
  text-align: center;
  margin-top: var(--space-sm);
  font-style: italic;
}

.flashcard-source {
  font-size: var(--fs-xs);
  color: var(--c-text-muted);
  margin-top: auto;
  padding-top: var(--space-md);
}

.flashcard-meaning {
  font-size: var(--fs-h2);
  color: var(--c-secondary);
  margin-top: var(--space-sm);
}

.flashcard-books {
  font-size: var(--fs-small);
  color: var(--c-text-light);
  margin-top: var(--space-sm);
}

.flashcard-hint {
  font-size: var(--fs-xs);
  color: var(--c-text-muted);
  margin-top: auto;
  padding-top: var(--space-md);
}

/* Rating buttons row */
.rating-buttons {
  display: flex;
  gap: var(--space-sm);
  padding: var(--space-md);
  justify-content: center;
  flex-shrink: 0;
}

/* Review complete screen */
.review-complete {
  text-align: center;
  padding: var(--space-xl);
}

.review-complete .complete-emoji {
  font-size: 4rem;
  animation: celebrateBounce 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.review-complete .complete-title {
  font-family: var(--font-display);
  font-size: var(--fs-h1);
  margin: var(--space-md) 0;
}

.review-complete .complete-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-sm);
  margin: var(--space-lg) 0;
}

/* ═══ GAMES ═══ */
.game-container {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: var(--space-md);
}

.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-lg);
}

.game-score {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  color: var(--c-accent-dark);
  display: flex;
  align-items: center;
  gap: 4px;
}

.game-timer {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  color: var(--c-primary);
}

.game-progress-text {
  font-family: var(--font-display);
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

.game-question {
  text-align: center;
  margin-bottom: var(--space-lg);
}

.game-image {
  width: 100%;
  max-width: 560px;
  max-height: min(38vh, 360px);
  object-fit: contain;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin: 0 auto var(--space-md);
}

.game-word-display {
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--c-primary);
  text-align: center;
  margin-bottom: var(--space-md);
}

.game-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-sm);
}

.game-option {
  padding: var(--space-md);
  border-radius: var(--radius-lg);
  background: var(--c-card);
  box-shadow: var(--shadow-card);
  text-align: center;
  font-family: var(--font-display);
  font-size: var(--fs-body);
  font-weight: 500;
  transition: all 0.15s ease;
  border: 3px solid transparent;
  min-height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.game-option:active {
  transform: scale(0.96);
}

.game-option.correct {
  border-color: var(--c-success);
  background: var(--c-success-light);
  animation: correctPop 0.4s ease;
}

.game-option.wrong {
  border-color: var(--c-danger);
  background: #FFF0F0;
  animation: shake 0.4s ease;
}

.game-option.selected {
  border-color: var(--c-secondary);
  background: var(--c-secondary-light);
}

.game-option img {
  width: 100%;
  height: 80px;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.game-options-image {
  width: min(100%, 1120px);
  margin: 0 auto;
  gap: clamp(12px, 1.4vw, 20px);
  align-items: stretch;
}

.game-options-image.game-options-portrait {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.game-options-image.game-options-landscape {
  grid-template-columns: repeat(2, minmax(220px, 1fr));
}

.game-option-image {
  padding: 10px;
  background: #f7f7f4;
}

.game-option-image.game-options-portrait {
  min-height: clamp(180px, 30vh, 320px);
}

.game-option-image.game-options-landscape {
  min-height: clamp(120px, 16vh, 180px);
}

.game-option-image .game-option-image-asset {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: inherit;
}

/* Sentence chips */
.game-chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  justify-content: center;
  padding: var(--space-md) 0;
}

.game-chip {
  padding: 10px 18px;
  border-radius: var(--radius-full);
  background: var(--c-card);
  box-shadow: var(--shadow-card);
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  cursor: pointer;
  transition: all 0.2s ease;
  user-select: none;
}

.game-chip:active {
  transform: scale(0.92);
}

.game-chip.placed {
  background: var(--c-secondary);
  color: white;
  box-shadow: none;
}

.game-chip.available {
  background: var(--c-card);
}

.game-sentence-area {
  min-height: 60px;
  border: 2px dashed var(--c-border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
}

.game-sentence-area.correct {
  border-color: var(--c-success);
  background: var(--c-success-light);
}

.game-sentence-area.wrong {
  border-color: var(--c-danger);
  background: #FFF0F0;
}

.game-result {
  text-align: center;
  padding: var(--space-xl);
}

.game-result .result-score {
  font-family: var(--font-display);
  font-size: 3rem;
  color: var(--c-accent-dark);
}

.combo-badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--c-accent), var(--c-warning));
  color: var(--c-text);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-small);
  animation: comboPop 0.3s ease;
}

.score-popup {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-family: var(--font-display);
  font-size: 3rem;
  color: var(--c-accent-dark);
  text-shadow: 2px 2px 0 rgba(0,0,0,0.1);
  animation: scoreFloat 0.8s ease forwards;
  pointer-events: none;
  z-index: 300;
}

/* Game selection menu */
.game-menu {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  padding-top: var(--space-md);
}

.game-menu-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: var(--c-card);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
  cursor: pointer;
  transition: all 0.2s ease;
}

.game-menu-card:active {
  transform: scale(0.97);
}

.game-menu-card .game-menu-icon {
  font-size: 2.5rem;
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  flex-shrink: 0;
}

.game-menu-card:nth-child(1) .game-menu-icon { background: #FFE8E8; }
.game-menu-card:nth-child(2) .game-menu-icon { background: #E8F5FF; }
.game-menu-card:nth-child(3) .game-menu-icon { background: #FFF3E0; }

.game-menu-card .game-menu-info {
  flex: 1;
}

.game-menu-card .game-menu-title {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  font-weight: 500;
}

.game-menu-card .game-menu-desc {
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

/* ═══ WORD LIBRARY ═══ */
.word-filters {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}

.word-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.word-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  background: var(--c-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: transform 0.15s ease;
}

.word-item:active {
  transform: scale(0.98);
}

.word-item .word-text {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  font-weight: 500;
  flex: 1;
}

.word-item .word-meta {
  font-size: var(--fs-xs);
  color: var(--c-text-light);
}

.word-item .word-books-count {
  font-size: var(--fs-xs);
  color: var(--c-text-muted);
}

/* Word detail page */
.word-detail {
  padding: var(--space-lg);
}

.word-detail-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.word-detail-word {
  font-family: var(--font-display);
  font-size: 2.5rem;
  color: var(--c-primary);
}

.word-detail-meaning {
  font-size: var(--fs-h2);
  color: var(--c-secondary);
  margin-top: var(--space-sm);
}

.word-appearances {
  margin-top: var(--space-lg);
}

.word-appearance {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-md);
  background: var(--c-card);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-sm);
  box-shadow: var(--shadow-sm);
}

.word-appearance img {
  width: 80px;
  height: 60px;
  object-fit: cover;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.word-appearance .appearance-info {
  flex: 1;
}

.word-appearance .appearance-sentence {
  font-style: italic;
  color: var(--c-text-light);
}

.word-appearance .appearance-book {
  font-size: var(--fs-xs);
  color: var(--c-text-muted);
}

/* ═══ STATS PAGE ═══ */
.stats-section {
  margin-bottom: var(--space-xl);
}

.chart-container {
  background: var(--c-card);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-sm);
}

.bar-chart {
  display: flex;
  align-items: flex-end;
  gap: var(--space-sm);
  height: 120px;
  padding-top: var(--space-md);
}

.bar-chart .bar {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.bar-chart .bar-fill {
  width: 100%;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  background: linear-gradient(180deg, var(--c-secondary), var(--c-secondary-dark));
  transition: height 0.5s cubic-bezier(0.22, 1, 0.36, 1);
  min-height: 4px;
}

.bar-chart .bar-label {
  font-size: var(--fs-xs);
  color: var(--c-text-muted);
}

.bar-chart .bar-value {
  font-size: var(--fs-xs);
  font-weight: 700;
  color: var(--c-text-light);
}

.level-progress {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  margin-top: var(--space-md);
}

.level-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.level-label {
  font-family: var(--font-display);
  font-weight: 600;
  width: 32px;
  text-transform: uppercase;
}

.level-bar {
  flex: 1;
}

.level-pct {
  font-size: var(--fs-small);
  font-weight: 600;
  width: 40px;
  text-align: right;
  color: var(--c-text-light);
}

/* ═══ SETTINGS ═══ */
.settings-group {
  margin-bottom: var(--space-xl);
}

.settings-group-title {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--c-border-light);
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--c-border-light);
}

.setting-label {
  font-weight: 600;
}

.setting-desc {
  font-size: var(--fs-small);
  color: var(--c-text-light);
}

.setting-value {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

/* Toggle switch */
.toggle {
  position: relative;
  width: 52px;
  height: 28px;
  background: var(--c-border);
  border-radius: 14px;
  cursor: pointer;
  transition: background 0.2s ease;
}

.toggle.on {
  background: var(--c-success);
}

.toggle::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 22px;
  height: 22px;
  background: white;
  border-radius: 50%;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease;
}

.toggle.on::after {
  transform: translateX(24px);
}

/* Number stepper */
.stepper {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.stepper .stepper-btn {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--c-border-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
}

.stepper .stepper-value {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  min-width: 28px;
  text-align: center;
}

/* ═══ LISTEN MODE ═══ */
.listen-player {
  background: var(--c-card);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-lg);
  text-align: center;
}

.listen-cover {
  width: 200px;
  height: 200px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin: 0 auto var(--space-lg);
}

.listen-title {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  margin-bottom: var(--space-sm);
}

.listen-subtitle {
  font-size: var(--fs-small);
  color: var(--c-text-light);
  margin-bottom: var(--space-lg);
}

.listen-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
}

.listen-btn-play {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--c-primary);
  color: white;
  font-size: 1.8rem;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(255,107,107,0.3);
  transition: all 0.15s ease;
}

.listen-btn-play:active {
  transform: scale(0.92);
}

.listen-progress-bar {
  width: 100%;
  height: 6px;
  background: var(--c-border-light);
  border-radius: 3px;
  margin: var(--space-lg) 0 var(--space-md);
  overflow: hidden;
  cursor: pointer;
}

.listen-progress-fill {
  height: 100%;
  background: var(--c-primary);
  border-radius: 3px;
  transition: width 0.3s linear;
}

.listen-mode-selector {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  margin-top: var(--space-lg);
  flex-wrap: wrap;
}

/* ═══ ACHIEVEMENTS ═══ */
.achievement-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-sm);
}

.achievement-badge {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: var(--space-md);
  border-radius: var(--radius-lg);
  background: var(--c-card);
  box-shadow: var(--shadow-sm);
  text-align: center;
}

.achievement-badge.locked {
  opacity: 0.4;
  filter: grayscale(1);
}

.achievement-badge .achievement-icon {
  font-size: 2rem;
}

.achievement-badge .achievement-name {
  font-size: var(--fs-xs);
  font-weight: 600;
  line-height: 1.2;
}

/* Achievement unlock popup */
.achievement-popup {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 500;
  background: rgba(0,0,0,0.5);
  animation: fadeIn 0.3s ease;
}

.achievement-popup-content {
  background: var(--c-card);
  border-radius: var(--radius-xl);
  padding: var(--space-2xl);
  text-align: center;
  max-width: 320px;
  animation: popIn 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.achievement-popup-icon {
  font-size: 5rem;
  animation: celebrateBounce 0.8s ease;
}

.achievement-popup-title {
  font-family: var(--font-display);
  font-size: var(--fs-h1);
  margin: var(--space-md) 0 var(--space-sm);
}

.achievement-popup-desc {
  color: var(--c-text-light);
  margin-bottom: var(--space-lg);
}

/* ═══ MODAL / OVERLAY ═══ */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 150;
  animation: fadeIn 0.2s ease;
}

/* ═══ QUIZ ═══ */
.quiz-container {
  padding: var(--space-sm) var(--space-md) var(--space-md);
  width: min(100%, 980px);
  margin: 0 auto;
}

.quiz-question-text {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  text-align: center;
  margin-bottom: var(--space-md);
  line-height: 1.3;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

.quiz-option {
  padding: var(--space-md);
  border-radius: var(--radius-lg);
  background: var(--c-card);
  box-shadow: var(--shadow-card);
  cursor: pointer;
  transition: all 0.15s ease;
  border: 3px solid transparent;
  text-align: center;
}

.quiz-option img {
  width: 100%;
  height: 120px;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.quiz-options-image {
  width: min(100%, 1120px);
  margin: 0 auto;
  gap: clamp(12px, 1.4vw, 20px);
  align-items: stretch;
}

.quiz-options-portrait {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.quiz-options-landscape {
  grid-template-columns: repeat(2, minmax(220px, 1fr));
}

.quiz-option-image {
  padding: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f7f7f4;
}

.quiz-option-image img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: inherit;
}

.quiz-option-image.quiz-options-portrait {
  height: clamp(180px, 30vh, 320px);
}

.quiz-option-image.quiz-options-landscape {
  height: clamp(120px, 16vh, 180px);
}

.quiz-option.correct {
  border-color: var(--c-success);
  background: var(--c-success-light);
}

.quiz-option.wrong {
  border-color: var(--c-danger);
  background: #FFF0F0;
}

/* ═══ PARENT PIN ═══ */
.pin-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 400;
}

.pin-dialog {
  background: var(--c-card);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  text-align: center;
  max-width: 300px;
  width: 90%;
}

.pin-input {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  margin: var(--space-lg) 0;
}

.pin-dot {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--c-border);
  transition: all 0.2s ease;
}

.pin-dot.filled {
  background: var(--c-primary);
  transform: scale(1.2);
}

.pin-numpad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-sm);
}

.pin-key {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--c-border-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  margin: 0 auto;
  transition: all 0.1s ease;
}

.pin-key:active {
  background: var(--c-border);
  transform: scale(0.9);
}

/* ═══ EMPTY / LOADING STATES ═══ */
.empty-state {
  text-align: center;
  padding: var(--space-2xl) var(--space-lg);
}

.empty-state .empty-icon {
  font-size: 4rem;
  margin-bottom: var(--space-md);
  opacity: 0.6;
}

.empty-state .empty-text {
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  color: var(--c-text-light);
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--c-border-light);
  border-top-color: var(--c-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: var(--space-xl) auto;
}

/* ═══ CROSS-BOOK HINT ═══ */
.cross-book-hint {
  background: linear-gradient(135deg, #F0F7FF, #E8F5FF);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  margin: var(--space-sm) 0;
  font-size: var(--fs-small);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  border-left: 4px solid var(--c-secondary);
}

.cross-book-hint .hint-icon {
  font-size: 1.3rem;
}

/* ═══ ANIMATIONS ═══ */
@keyframes pageFadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes pageSlideIn {
  from { opacity: 0; transform: translateX(30px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes slideUp {
  from { transform: translate(-50%, 100%); }
  to { transform: translate(-50%, 0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes wordBounce {
  0% { transform: scale(0.5); opacity: 0; }
  60% { transform: scale(1.1); }
  100% { transform: scale(1); opacity: 1; }
}

@keyframes celebrateBounce {
  0% { transform: scale(0); }
  50% { transform: scale(1.3); }
  70% { transform: scale(0.9); }
  100% { transform: scale(1); }
}

@keyframes correctPop {
  0% { transform: scale(1); }
  50% { transform: scale(1.06); }
  100% { transform: scale(1); }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

@keyframes comboPop {
  0% { transform: scale(0.5); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

@keyframes scoreFloat {
  0% { transform: translate(-50%, -50%) scale(0.5); opacity: 0; }
  30% { transform: translate(-50%, -50%) scale(1.3); opacity: 1; }
  100% { transform: translate(-50%, -80%) scale(1); opacity: 0; }
}

@keyframes popIn {
  0% { transform: scale(0.3); opacity: 0; }
  60% { transform: scale(1.05); }
  100% { transform: scale(1); opacity: 1; }
}

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

@keyframes starFloat {
  0% { transform: translateY(0) scale(1); opacity: 1; }
  100% { transform: translateY(-40px) scale(0.5); opacity: 0; }
}

/* Star animation helper */
.star-burst {
  position: absolute;
  pointer-events: none;
  font-size: 1.5rem;
  animation: starFloat 0.8s ease forwards;
}

/* ═══ UTILITY ═══ */
.text-center { text-align: center; }
.text-muted { color: var(--c-text-light); }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.gap-sm { gap: var(--space-sm); }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.flex-1 { flex: 1; }
.hidden { display: none !important; }

/* ═══════════════════════════════════════════════
   RESPONSIVE BREAKPOINTS
   ═══════════════════════════════════════════════ */

/* ── Small phone (<380px) ── */
@media (max-width: 380px) {
  :root {
    --fs-hero: 1.7rem;
    --fs-h1: 1.4rem;
    --fs-h2: 1.15rem;
  }

  .book-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .stat-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .achievement-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .rating-buttons {
    gap: var(--space-xs);
  }

  .btn-emoji {
    min-width: 62px;
    padding: 10px 6px;
  }
}

/* ── Tablet (768px+) — wider content, more columns ── */
@media (min-width: 768px) {
  :root {
    --max-width: 720px;
    --fs-hero: 2.4rem;
    --fs-h1: 1.8rem;
  }

  .book-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .stat-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-md);
  }

  .achievement-grid {
    grid-template-columns: repeat(5, 1fr);
  }

  .game-menu {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-md);
  }

  .game-menu-card {
    flex-direction: column;
    text-align: center;
  }

  /* Wider flashcard */
  .flashcard {
    max-width: 440px;
  }

  .flashcard-inner {
    min-height: 480px;
  }

  /* Wider quiz options */
  .quiz-options {
    max-width: 560px;
    margin: 0 auto;
  }

  .quiz-options-image {
    max-width: 1120px;
  }

  .quiz-option-image.quiz-options-portrait {
    height: clamp(210px, 34vh, 360px);
  }

  .quiz-option-image.quiz-options-landscape {
    height: clamp(140px, 18vh, 220px);
  }

  .game-options {
    max-width: 560px;
    margin: 0 auto;
  }

  .game-options-image {
    max-width: 1120px;
  }

  .game-option-image.game-options-portrait {
    min-height: clamp(210px, 34vh, 360px);
  }

  .game-option-image.game-options-landscape {
    min-height: clamp(140px, 18vh, 220px);
  }

  /* Rating buttons more spacious */
  .btn-emoji {
    min-width: 90px;
    padding: 14px 12px;
  }

  /* Reader: larger image */
  .reader-image-wrapper {
    max-width: 600px;
    margin: 0 auto;
  }

  .reader-text {
    font-size: 1.7rem;
  }

  .preview-word {
    font-size: 3rem;
  }

  /* Listen player centered */
  .listen-player {
    max-width: 500px;
    margin: 0 auto;
  }

  /* Word list in 2 columns */
  .word-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-sm);
  }
}

/* ── Desktop (1024px+) — sidebar nav, wide layout ── */
@media (min-width: 1024px) {
  :root {
    --max-width: var(--content-max-width);
  }

  /* Sidebar navigation */
  .app-nav {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    right: auto;
    width: var(--sidebar-width);
    max-width: var(--sidebar-width);
    height: 100vh;
    border-top: none;
    border-right: 1px solid var(--c-border-light);
    box-shadow: 2px 0 12px rgba(0,0,0,0.04);
    padding: 0;
    padding-bottom: 0;
    transform: none;
    transition: transform 0.3s ease;
  }

  .app-nav.nav-hidden {
    transform: translateX(-100%);
  }

  /* Show brand logo in sidebar */
  .nav-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-lg) var(--space-md);
    border-bottom: 1px solid var(--c-border-light);
  }

  .nav-brand-icon {
    font-size: 1.6rem;
  }

  .nav-brand-text {
    font-family: var(--font-display);
    font-size: var(--fs-h3);
    font-weight: 600;
    color: var(--c-primary);
  }

  /* Vertical nav items */
  .nav-items {
    flex-direction: column;
    justify-content: flex-start;
    align-items: stretch;
    padding: var(--space-sm);
    gap: 2px;
    overflow-y: auto;
  }

  /* Show all nav items on desktop */
  .nav-item[data-page="words"],
  .nav-item[data-page="listen"] {
    display: flex;
  }

  .nav-item {
    flex-direction: row;
    justify-content: flex-start;
    gap: var(--space-md);
    padding: 12px var(--space-md);
    border-radius: var(--radius-md);
    min-width: unset;
  }

  .nav-item .nav-icon {
    font-size: 1.3rem;
  }

  .nav-item .nav-label {
    font-size: var(--fs-body);
  }

  .nav-item.active {
    background: var(--c-bg-warm);
  }

  .nav-item.active::after {
    display: none;
  }

  .nav-item:hover {
    background: var(--c-border-light);
  }

  .nav-badge {
    position: static;
    margin-left: auto;
  }

  /* Shift app content to the right */
  #app {
    margin-left: var(--sidebar-width);
    max-width: calc(100vw - var(--sidebar-width));
    padding-bottom: var(--space-lg);
  }

  .page {
    max-width: var(--content-max-width);
    margin: 0 auto;
    padding: var(--space-xl) var(--space-xl);
  }

  /* Full-page views (reader, review session): cover screen but respect sidebar */
  .page.full-page {
    left: var(--sidebar-width);
    right: 0;
    max-width: none;
    padding: 0;
    width: auto;
  }

  /* Book grid: 5 columns on desktop */
  .book-grid {
    grid-template-columns: repeat(5, 1fr);
    gap: var(--space-lg);
  }

  .book-card {
    transition: transform 0.2s ease, box-shadow 0.2s ease;
  }

  .book-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
  }

  /* Book modal: wider and centered */
  .book-modal {
    left: calc(var(--sidebar-width) + 50%);
    transform: translateX(-50%);
    max-width: 500px;
    border-radius: var(--radius-xl);
    bottom: auto;
    top: 50%;
    animation: popIn 0.3s cubic-bezier(0.22, 1, 0.36, 1);
    transform: translate(-50%, -50%);
  }

  /* Reader: side-by-side image + text on wide screens */
  .reader-body {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--space-xl);
    max-width: 1000px;
    margin: 0 auto;
    padding: var(--space-lg) var(--space-xl);
  }

  .reader-image-wrapper {
    flex: 1;
    max-width: 55%;
    position: sticky;
    top: var(--space-lg);
  }

  .reader-text {
    flex: 1;
    text-align: left;
    font-size: 1.8rem;
    padding-top: var(--space-xl);
  }

  .reader-controls {
    max-width: 1000px;
    margin: 0 auto;
  }

  .reader-nav {
    max-width: 1000px;
    margin: 0 auto;
  }

  .mode-toggles {
    max-width: 1000px;
    margin: 0 auto;
    padding: var(--space-sm) 0;
  }

  /* Preview card: wider layout */
  .preview-card {
    text-align: left;
  }

  .preview-word {
    font-size: 3.5rem;
  }

  /* Flashcard: larger */
  .flashcard {
    max-width: 500px;
  }

  .flashcard-inner {
    min-height: 520px;
  }

  .flashcard-word {
    font-size: 2.6rem;
  }

  .flashcard-image {
    max-height: 250px;
  }

  /* Stats: 2-column layout */
  .stats-section {
    max-width: var(--content-max-width);
  }

  .chart-container {
    padding: var(--space-xl);
  }

  .bar-chart {
    height: 160px;
  }

  /* Achievement grid: 6 columns */
  .achievement-grid {
    grid-template-columns: repeat(6, 1fr);
  }

  /* Settings: constrained width */
  .settings-group {
    max-width: 600px;
  }

  /* Listen: centered player */
  .listen-player {
    max-width: 500px;
    margin: var(--space-lg) auto;
  }

  /* Word list: 3 columns */
  .word-list {
    grid-template-columns: repeat(3, 1fr);
  }

  /* Word detail: side-by-side appearances */
  .word-appearances {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
  }

  .word-appearances .section-title {
    grid-column: 1 / -1;
  }

  /* Game: constrain width for playability */
  .game-container {
    max-width: 700px;
    margin: 0 auto;
  }

  .game-options {
    max-width: 600px;
    margin: 0 auto;
  }

  .game-options-image {
    max-width: 1120px;
  }

  .game-chips {
    max-width: 600px;
    margin: 0 auto;
  }

  /* Stat cards hover effect */
  .stat-card {
    transition: transform 0.2s ease;
  }

  .stat-card:hover {
    transform: translateY(-2px);
  }

  /* Plan items hover */
  .plan-item:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-md);
  }

  /* Home: 2-column layout for plan + stats */
  .today-plan {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-sm);
  }

  .today-plan .section-title {
    grid-column: 1 / -1;
  }

  /* Streak display: wider */
  .streak-display {
    max-width: 500px;
  }
}

/* ── Large desktop (1400px+) — even wider ── */
@media (min-width: 1400px) {
  :root {
    --sidebar-width: 260px;
    --content-max-width: 1100px;
  }

  .book-grid {
    grid-template-columns: repeat(6, 1fr);
  }

  .achievement-grid {
    grid-template-columns: repeat(8, 1fr);
  }

  .reader-body {
    max-width: 1100px;
  }

  .word-list {
    grid-template-columns: repeat(4, 1fr);
  }

  .today-plan {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ── Landscape orientation ── */
@media (orientation: landscape) and (max-height: 500px) {
  /* Mobile landscape: reduce heights */
  .reader-image {
    max-height: 55vh;
  }

  .flashcard-inner {
    min-height: 320px;
  }

  .flashcard-image {
    max-height: 140px;
  }
}