/* ==========================================================================
   TOEIC STUDY & MASTERY HUB - STYLES
   Designed for foundational learners (Mất gốc -> 100% Mastery)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;600&display=swap');

:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: rgba(37, 99, 235, 0.1);
  --primary-glow: rgba(37, 99, 235, 0.35);

  --accent-purple: #8b5cf6;
  --accent-purple-light: rgba(139, 92, 246, 0.12);
  
  --accent-orange: #f97316;
  --accent-orange-light: rgba(249, 115, 22, 0.12);

  --success: #10b981;
  --success-light: rgba(16, 185, 129, 0.12);
  --danger: #ef4444;
  --danger-light: rgba(239, 68, 68, 0.12);
  --warning: #f59e0b;

  --bg-app: #f8fafc;
  --bg-card: #ffffff;
  --bg-card-subtle: #f1f5f9;
  --bg-glass: rgba(255, 255, 255, 0.88);

  --border-subtle: #e2e8f0;
  --border-focus: #94a3b8;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 20px -3px rgba(0, 0, 0, 0.1);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-app: #0b0f19;
  --bg-card: #151d2f;
  --bg-card-subtle: #1e293b;
  --bg-glass: rgba(21, 29, 47, 0.9);

  --border-subtle: #243049;
  --border-focus: #3b82f6;

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
}

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

html, body {
  overflow-x: clip;
  max-width: 100%;
  position: relative;
}

body {
  font-family: 'Plus Jakarta Sans', system-ui, sans-serif;
  background-color: var(--bg-app);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.study-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-glass);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand-title-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}

.btn-back-test {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
  transition: var(--transition);
}

.btn-back-test:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.mastery-progress-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-card);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-subtle);
  font-size: 13px;
  font-weight: 700;
}

.mastery-progress-pill .val {
  color: var(--success);
}

/* Study Exam Selection Bar */
.study-exam-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  background: var(--bg-card-subtle);
  border-bottom: 1px solid var(--border-subtle);
  padding: 10px 24px;
  flex-wrap: wrap;
}

.study-exam-label {
  font-size: 13px;
  font-weight: 800;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 6px;
}

.study-mode-pills {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.study-pill-btn {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1.5px solid var(--border-subtle);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

.study-pill-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-1px);
}

.study-pill-btn.active {
  background: linear-gradient(135deg, var(--primary), var(--accent-purple));
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 12px var(--primary-glow);
}

.study-back-exam-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: linear-gradient(135deg, var(--accent-orange), #ea580c);
  color: #fff;
  text-decoration: none;
  font-size: 12.5px;
  font-weight: 700;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  box-shadow: 0 2px 8px rgba(249, 115, 22, 0.35);
  transition: var(--transition);
}

.study-back-exam-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(249, 115, 22, 0.45);
  color: #fff;
}

/* Main Navigation Tabs */
.study-tabs-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: var(--bg-card);
  border-bottom: 1px solid var(--border-subtle);
  padding: 12px 24px;
}

.study-tab-btn {
  background: none;
  border: 1.5px solid var(--border-subtle);
  padding: 10px 20px;
  border-radius: var(--radius-full);
  font-size: 13.5px;
  font-weight: 700;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition);
}

.study-tab-btn:hover {
  background: var(--bg-card-subtle);
  color: var(--text-primary);
}

.study-tab-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  box-shadow: 0 4px 14px var(--primary-glow);
}

/* Main Container Grid */
.study-main {
  flex: 1;
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 24px;
  padding: 24px;
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
}

.study-content-area {
  min-width: 0;
}

/* Question Mastery Card */
.mastery-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
}

.mastery-badge-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.part-indicator-tag {
  background: linear-gradient(135deg, var(--primary), var(--accent-purple));
  color: #fff;
  font-weight: 800;
  font-size: 12.5px;
  padding: 5px 14px;
  border-radius: var(--radius-full);
}

/* Audio Player Section inside Study Card - STICKY TOP */
.study-audio-box {
  position: sticky;
  top: 68px;
  z-index: 85;
  background: var(--bg-card);
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
  backdrop-filter: blur(12px);
  transition: var(--transition);
}

.study-audio-box.is-playing {
  border-color: var(--primary);
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.25);
}

.audio-box-badge {
  font-size: 11.5px;
  font-weight: 800;
  color: #fff;
  background: linear-gradient(135deg, var(--primary), var(--accent-purple));
  padding: 4px 10px;
  border-radius: var(--radius-full);
  white-space: nowrap;
  letter-spacing: -0.01em;
}

.btn-speed-slow {
  background: var(--accent-orange-light);
  color: var(--accent-orange);
  border: 1px solid rgba(249, 115, 22, 0.3);
  font-size: 12px;
  font-weight: 700;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition);
}

.btn-speed-slow:hover, .btn-speed-slow.active {
  background: var(--accent-orange);
  color: #fff;
}

/* Section Box: Vocab, Translation, Explanation */
.study-section-box {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 18px 20px;
  margin-bottom: 18px;
}

.study-section-title {
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.study-section-title.vocab { color: var(--primary); }
.study-section-title.trans { color: var(--accent-purple); }
.study-section-title.explain { color: var(--success); }
.study-section-title.trap { color: var(--danger); }

/* Vocabulary Chip / Tags */
.vocab-chips-container {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 10px;
}

.vocab-card-chip {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.vocab-word {
  font-size: 14px;
  font-weight: 700;
  color: var(--primary);
}

.vocab-ipa {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11.5px;
  color: var(--text-muted);
}

.vocab-meaning {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
}

/* Bilingual Translation Box */
.bilingual-box {
  font-size: 14.5px;
  line-height: 1.8;
  white-space: pre-line;
  color: var(--text-secondary);
}

/* Practice Interactive Drill inside Study Mode */
.interactive-drill-box {
  background: var(--bg-card);
  border: 2px solid var(--primary-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-top: 24px;
}

.drill-title {
  font-size: 16px;
  font-weight: 800;
  margin-bottom: 12px;
}

.drill-question-prompt {
  background: var(--bg-card-subtle);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 14px 18px;
  margin-bottom: 16px;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  box-shadow: var(--shadow-sm);
}

.drill-qnum-tag {
  background: var(--primary);
  color: #fff;
  font-size: 12px;
  font-weight: 800;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  flex-shrink: 0;
  margin-top: 1px;
}

.drill-qtext {
  font-size: 15.5px;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.5;
}

.drill-choices-list {
  display: grid;
  gap: 10px;
  margin-bottom: 18px;
}

.drill-choice-btn {
  text-align: left;
  background: var(--bg-card-subtle);
  border: 1.5px solid var(--border-subtle);
  padding: 12px 18px;
  border-radius: var(--radius-md);
  font-size: 14.5px;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  transition: var(--transition);
}

.drill-choice-btn:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.drill-choice-btn.selected {
  border-color: var(--primary);
  background: var(--primary-light);
  color: var(--primary);
}

.drill-choice-btn.is-correct {
  border-color: var(--success) !important;
  background: var(--success-light) !important;
  color: var(--success) !important;
}

.drill-choice-btn.is-wrong {
  border-color: var(--danger) !important;
  background: var(--danger-light) !important;
  color: var(--danger) !important;
}

.drill-feedback-banner {
  padding: 14px 18px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 700;
  margin-top: 14px;
  display: none !important;
}

.drill-feedback-banner.show-success {
  display: flex !important;
  align-items: center;
  justify-content: space-between;
  background: var(--success-light);
  color: var(--success);
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.drill-feedback-banner.show-error {
  display: block !important;
  background: var(--danger-light);
  color: var(--danger);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

/* ==========================================================================
   TAB 2: DICTATION TRAINER (NGHE CHÉP CHÍNH TẢ)
   ========================================================================== */
.dictation-container {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.dictation-hero {
  text-align: center;
  margin-bottom: 28px;
}

.dictation-hero h2 {
  font-size: 22px;
  font-weight: 800;
  margin-bottom: 6px;
}

.dictation-audio-center {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 24px;
}

.dictation-input-area {
  max-width: 600px;
  margin: 0 auto 20px auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.dictation-input-box {
  width: 100%;
  font-size: 18px;
  padding: 14px 18px;
  border-radius: var(--radius-md);
  border: 2px solid var(--border-subtle);
  background: var(--bg-card-subtle);
  color: var(--text-primary);
  font-family: inherit;
  font-weight: 600;
  text-align: center;
  transition: var(--transition);
}

.dictation-input-box:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 15px var(--primary-glow);
}

.dictation-hint-text {
  font-size: 13px;
  color: var(--text-muted);
  text-align: center;
}

/* ==========================================================================
   TAB 3: VOCABULARY VAULT (FLASHCARDS)
   ========================================================================== */
/* ==========================================================================
   TAB 3: VOCABULARY VAULT (FLASHCARDS)
   ========================================================================== */
.vocab-vault-wrap {
  display: flex;
  flex-direction: column;
}

.vocab-vault-header {
  margin-bottom: 20px;
}

.vocab-vault-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
  background: var(--bg-card);
  padding: 16px 20px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
}

.vocab-search-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: 9999px;
  padding: 8px 16px;
  flex: 1;
  max-width: 450px;
}

.vocab-search-input {
  border: none;
  background: transparent;
  outline: none;
  color: var(--text-primary);
  font-size: 13.5px;
  width: 100%;
}

.vocab-part-filters {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}

.vocab-filter-pill {
  padding: 6px 14px;
  border-radius: 9999px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-card);
  color: var(--text-secondary);
  font-size: 12.5px;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}

.vocab-filter-pill:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.vocab-filter-pill.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
}

.flashcards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 16px;
}

.flashcard-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 20px 22px;
  cursor: pointer;
  transition: var(--transition);
  min-height: 190px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.flashcard-item:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.vocab-badge-part {
  font-size: 11px;
  font-weight: 800;
  color: var(--text-muted);
  background: var(--bg-card-subtle);
  padding: 3px 8px;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
}

.vocab-speak-btn {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: 9999px;
  padding: 3px 10px;
  font-size: 11.5px;
  font-weight: 700;
  color: var(--primary);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 4px;
}

.vocab-speak-btn:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.flashcard-front {
  font-size: 19px;
  font-weight: 800;
  color: var(--text-primary);
  margin-top: 6px;
  margin-bottom: 2px;
}

.flashcard-ipa {
  font-size: 12.5px;
  color: var(--text-muted);
  font-family: monospace;
}

.flashcard-back {
  border-top: 1px dashed var(--border-subtle);
  padding-top: 12px;
  margin-top: 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.flashcard-meaning {
  font-size: 14.5px;
  font-weight: 700;
  color: var(--primary);
  line-height: 1.4;
}

.vocab-jump-btn {
  align-self: flex-start;
  background: transparent;
  border: none;
  color: var(--accent-orange);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  padding: 0;
  margin-top: 4px;
  transition: var(--transition);
}

.vocab-jump-btn:hover {
  text-decoration: underline;
}

/* Right Question Selector Matrix */
.study-sidebar {
  position: sticky;
  top: 130px;
  max-height: calc(100vh - 150px);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
}

.study-matrix-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
  overflow-y: auto;
  max-height: calc(100vh - 260px);
  padding-right: 4px;
}

.study-q-btn {
  height: 34px;
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.study-q-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.study-q-btn.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.study-q-btn.mastered {
  background: var(--success) !important;
  color: #fff !important;
  border-color: var(--success) !important;
}

/* ==========================================================================
   MOBILE & RESPONSIVE DESIGN (OPTIMIZED FOR ALL PHONES & TABLETS)
   ========================================================================== */
.mobile-matrix-trigger {
  display: none !important;
}

@media (max-width: 1024px) {
  .study-main {
    grid-template-columns: 1fr;
    padding: 16px;
  }
  .study-sidebar {
    display: none;
  }
  .mobile-matrix-trigger {
    display: flex !important;
  }
  .study-tabs-nav {
    overflow-x: auto;
    flex-wrap: nowrap;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
  }
  .study-tabs-nav::-webkit-scrollbar {
    display: none;
  }
  .study-tab-btn {
    flex-shrink: 0;
  }
}

@media (max-width: 768px) {
  /* Header: Sleek, compact 1-line layout */
  .study-header {
    padding: 6px 10px;
    height: 48px;
    top: 0;
    width: 100%;
    max-width: 100vw;
    box-sizing: border-box;
    overflow: hidden;
    gap: 6px;
    justify-content: space-between;
  }

  .btn-back-test {
    padding: 6px;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
  }

  .btn-back-text {
    display: none !important; /* Hide "Thi Thử" text, arrow icon only */
  }

  .brand-title-wrap {
    gap: 6px;
    min-width: 0;
    flex-shrink: 1;
    overflow: hidden;
    display: flex;
    align-items: center;
  }

  .brand-title-wrap h1 {
    font-size: 13px !important;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 120px;
  }

  .brand-title-wrap p {
    display: none !important; /* Hide subtitle to keep single line */
  }

  .mastery-progress-pill {
    display: none !important; /* Hide on mobile to prevent header overflow */
  }

  .theme-text {
    display: none !important;
  }

  .mobile-matrix-text {
    display: none !important; /* Hide text "200 Câu", icon only */
  }

  .mobile-matrix-trigger {
    padding: 6px 8px;
    height: 32px;
    font-size: 13px;
    display: flex !important;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    border-color: var(--primary);
    color: var(--primary);
  }

  #study-theme-toggle {
    padding: 6px !important;
    width: 32px;
    height: 32px;
    display: flex !important;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
  }

  /* Navigation Tabs: Horizontal touch scrollable with clean pills */
  .study-tabs-nav {
    padding: 6px 8px;
    gap: 6px;
    overflow-x: auto;
    flex-wrap: nowrap;
    justify-content: flex-start;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
    width: 100%;
    max-width: 100vw;
    box-sizing: border-box;
  }
  .study-tabs-nav::-webkit-scrollbar {
    display: none;
  }

  .study-tab-btn {
    padding: 6px 12px;
    font-size: 12px;
    white-space: nowrap;
    flex-shrink: 0;
  }

  /* Main Container */
  .study-main {
    padding: 10px 8px 78px 8px !important;
    gap: 12px;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
  }

  .study-content-area {
    width: 100%;
    max-width: 100%;
    min-width: 0;
    box-sizing: border-box;
  }

  .mastery-card {
    padding: 14px 10px;
    border-radius: var(--radius-md);
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
  }

  .mastery-badge-header {
    margin-bottom: 10px;
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
    width: 100%;
  }

  .part-indicator-tag {
    font-size: 11px;
    padding: 3px 8px;
    max-width: 100%;
    white-space: nowrap;
  }

  /* Sticky Audio Bar: Fits 100% on phone, no overflow, sticks below 48px header */
  .study-audio-box {
    position: -webkit-sticky !important;
    position: sticky !important;
    top: 48px !important;
    z-index: 95;
    background: var(--bg-card) !important;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25) !important;
    padding: 8px 6px;
    gap: 5px;
    margin-bottom: 14px;
    border-radius: var(--radius-md);
    flex-wrap: wrap;
    justify-content: flex-start;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
  }

  .audio-box-badge {
    font-size: 10.5px;
    padding: 3px 7px;
  }

  .btn-speed-slow {
    padding: 5px 8px;
    font-size: 11px;
  }

  #btn-play-normal {
    padding: 5px 12px !important;
    font-size: 11.5px !important;
    font-weight: 800;
  }

  #btn-replay-3s {
    padding: 5px 7px !important;
    font-size: 11px !important;
  }

  .study-audio-box .audio-shortcut-hint {
    display: none !important; /* Hide keyboard shortcut on phones */
  }

  /* Vocabulary Chips Box */
  .vocab-chips-container {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .vocab-card-chip {
    padding: 10px 12px;
  }

  .vocab-word {
    font-size: 15px;
  }

  /* Bilingual Translation Box */
  .bilingual-box {
    font-size: 13.5px;
    line-height: 1.6;
    padding: 10px 12px;
    overflow-wrap: break-word;
    word-break: break-word;
  }

  /* Interactive Drill Box */
  .interactive-drill-box {
    padding: 14px 12px;
    margin-top: 16px;
  }

  .drill-title {
    font-size: 14.5px;
    margin-bottom: 10px;
  }

  .drill-question-prompt {
    padding: 10px 12px;
    gap: 8px;
    margin-bottom: 12px;
  }

  .drill-qnum-tag {
    font-size: 10.5px;
    padding: 2px 6px;
  }

  .drill-qtext {
    font-size: 13.5px;
  }

  .drill-choice-btn {
    padding: 10px 12px;
    font-size: 13.5px;
    gap: 10px;
    min-height: 48px; /* Large touch target for fingers */
  }

  /* Navigation footer buttons */
  #btn-prev-lesson, #btn-next-lesson {
    flex: 1;
    justify-content: center;
    padding: 10px;
    font-size: 13px;
  }

  /* Tab 3: Vocabulary Vault Mobile */
  .vocab-vault-controls {
    padding: 12px;
    gap: 10px;
  }

  .vocab-search-wrap {
    max-width: 100%;
  }

  .vocab-part-filters {
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 4px;
    scrollbar-width: none;
  }
  .vocab-part-filters::-webkit-scrollbar {
    display: none;
  }

  .vocab-filter-pill {
    padding: 5px 12px;
    font-size: 11.5px;
    flex-shrink: 0;
  }

  .flashcards-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .flashcard-item {
    padding: 16px 14px;
    min-height: auto;
  }

  /* Safe padding for study-main on mobile to not be occluded by bottom nav */
  .study-main {
    padding-bottom: 78px !important;
  }

  .vocab-search-input {
    font-size: 16px !important; /* Prevents auto-zoom on iOS */
  }

  /* Mobile Floating Bottom Navigation Bar */
  .mobile-bottom-nav {
    display: flex !important;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 95;
    background: var(--bg-card);
    border-top: 1px solid var(--border-subtle);
    padding: 8px 12px calc(8px + env(safe-area-inset-bottom, 0px));
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.15);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
  }

  .mobile-nav-btn {
    flex: 1;
    height: 42px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
    font-weight: 700;
    font-size: 12.5px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-subtle);
    background: var(--bg-card-subtle);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
  }

  .mobile-nav-btn:active {
    transform: scale(0.96);
  }

  .mobile-nav-btn.primary {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
    box-shadow: 0 2px 10px rgba(37, 99, 235, 0.35);
  }

  .mobile-nav-center-btn {
    flex: 1.4;
    height: 42px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    border: 1.5px solid var(--primary);
    background: rgba(37, 99, 235, 0.08);
    cursor: pointer;
    transition: var(--transition);
  }

  .mobile-nav-center-btn:active {
    transform: scale(0.96);
    background: rgba(37, 99, 235, 0.18);
  }

  .mobile-nav-q-badge {
    font-size: 13px;
    font-weight: 800;
    color: var(--primary);
    line-height: 1.1;
  }

  .mobile-nav-matrix-hint {
    font-size: 9.5px;
    font-weight: 600;
    color: var(--text-secondary);
    opacity: 0.85;
    margin-top: 1px;
  }

  /* Dictation container padding on mobile */
  .dictation-container {
    padding: 16px 12px;
  }
  .dictation-hero h2 {
    font-size: 18px;
  }

  /* Feedback banner responsive */
  .drill-feedback-banner.show-success,
  .drill-feedback-banner.show-fail {
    flex-direction: column;
    gap: 10px;
    text-align: center;
  }
}

@media (max-width: 400px) {
  .mastery-badge-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }
}

/* Default: hidden on desktop screens */
@media (min-width: 769px) {
  .mobile-bottom-nav {
    display: none !important;
  }
}

/* Mobile Matrix Drawer Styles */
.mobile-matrix-drawer {
  position: fixed;
  inset: 0;
  z-index: 999;
  display: none;
}

.mobile-matrix-drawer.is-open {
  display: block;
}

.mobile-drawer-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(4px);
}

.mobile-drawer-content {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  max-height: 82vh;
  background: var(--bg-card);
  border-top: 2px solid var(--primary);
  border-radius: 20px 20px 0 0;
  padding: 16px 14px 24px;
  display: flex;
  flex-direction: column;
  box-shadow: 0 -8px 30px rgba(0, 0, 0, 0.4);
  animation: slideUpDrawer 0.25s ease-out;
}

@keyframes slideUpDrawer {
  from { transform: translateY(100%); }
  to { transform: translateY(0); }
}

.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-subtle);
}

.mobile-drawer-close {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: 50%;
  width: 32px;
  height: 32px;
  font-size: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
  cursor: pointer;
}

.study-matrix-grid.mobile-grid {
  overflow-y: auto;
  max-height: calc(82vh - 125px);
  padding: 8px 2px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

/* Zero Foundation Lifesaver Box */
.zero-foundation-box {
  background: #fffbeb;
  border: 2px dashed #f59e0b;
  border-radius: 12px;
  padding: 18px 20px;
  margin-bottom: 22px;
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.12);
  transition: var(--transition);
}

[data-theme="dark"] .zero-foundation-box {
  background: rgba(245, 158, 11, 0.1);
  border-color: #d97706;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.3);
}

.zero-foundation-header {
  font-size: 16px;
  font-weight: 800;
  color: #b45309;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

[data-theme="dark"] .zero-foundation-header {
  color: #fbbf24;
}

.zero-foundation-body {
  font-size: 15px;
  color: #451a03;
  line-height: 1.8;
  white-space: pre-line;
}

[data-theme="dark"] .zero-foundation-body {
  color: #fef3c7;
}

.zero-foundation-body b {
  color: #92400e;
}

[data-theme="dark"] .zero-foundation-body b {
  color: #fcd34d;
}

/* Study Exam Selection Bar & Pills */
.study-exam-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  background: var(--bg-card-subtle);
  border-bottom: 1px solid var(--border-subtle);
  padding: 10px 24px;
  flex-wrap: wrap;
}

.study-exam-label {
  font-size: 13px;
  font-weight: 800;
  color: var(--text-secondary);
}

.study-mode-pills {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.study-pill-btn {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1.5px solid var(--border-subtle);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}

.study-pill-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-1px);
}

.study-pill-btn.active {
  background: linear-gradient(135deg, var(--primary), #8b5cf6);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.35);
}

.btn-shuffle-random {
  background: linear-gradient(135deg, #ec4899, #8b5cf6) !important;
  color: #fff !important;
  font-weight: 800 !important;
  border: none !important;
  box-shadow: 0 3px 12px rgba(236, 72, 153, 0.4) !important;
  transition: all 0.2s ease !important;
}

.btn-shuffle-random:hover {
  transform: translateY(-1px) scale(1.04) !important;
  box-shadow: 0 6px 18px rgba(236, 72, 153, 0.55) !important;
}

.study-back-exam-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: linear-gradient(135deg, #10b981, #059669);
  color: #fff;
  text-decoration: none;
  font-size: 13px;
  font-weight: 800;
  padding: 7px 18px;
  border-radius: var(--radius-full);
  box-shadow: 0 3px 10px rgba(16, 185, 129, 0.35);
  transition: var(--transition);
}

.study-back-exam-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 5px 15px rgba(16, 185, 129, 0.5);
  color: #fff;
}