/* ================================================================
   VocabPro — Professional Vocabulary Flashcard App
   Design: Notion + Duolingo + Anki style, Japanese company feel
   ================================================================ */

/* ---------- CSS Variables ---------- */
:root {
  /* Colors - Light mode */
  --bg-primary:   #f0f4f8;
  --bg-surface:   #ffffff;
  --bg-surface-2: #f7f9fc;
  --bg-sidebar:   #1e2a3a;
  --border:       #e2e8f0;
  --border-soft:  #edf2f7;

  --text-primary:   #1a202c;
  --text-secondary: #4a5568;
  --text-muted:     #718096;
  --text-on-dark:   #e2e8f0;
  --text-sidebar:   #cbd5e0;

  /* Brand colors */
  --accent:        #4f6ef7;
  --accent-hover:  #3d5af1;
  --accent-light:  #ebf0ff;
  --accent-2:      #10b981;   /* green */
  --accent-3:      #f59e0b;   /* amber */
  --accent-4:      #ef4444;   /* red */
  --accent-5:      #8b5cf6;   /* purple */

  /* Card colors */
  --card-front-bg: linear-gradient(135deg, #4f6ef7 0%, #7b8ff7 100%);
  --card-back-bg:  #ffffff;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.05);
  --shadow-md:  0 4px 16px rgba(0,0,0,.10), 0 2px 4px rgba(0,0,0,.06);
  --shadow-lg:  0 8px 32px rgba(0,0,0,.12), 0 4px 8px rgba(0,0,0,.06);
  --shadow-card: 0 20px 60px rgba(79,110,247,.20), 0 4px 12px rgba(0,0,0,.08);

  /* Geometry */
  --radius-sm:  6px;
  --radius-md:  12px;
  --radius-lg:  20px;
  --radius-xl:  28px;
  --sidebar-w:  260px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-med:  0.25s ease;
  --transition-slow: 0.4s ease;
}

/* ---------- Dark mode ---------- */
.dark-mode {
  --bg-primary:   #0f172a;
  --bg-surface:   #1e293b;
  --bg-surface-2: #162032;
  --bg-sidebar:   #0d1929;
  --border:       #2d3748;
  --border-soft:  #1e2d3d;

  --text-primary:   #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted:     #64748b;
  --text-on-dark:   #e2e8f0;
  --text-sidebar:   #94a3b8;

  --accent-light:  #1e2d5a;
  --card-back-bg:  #1e293b;

  --shadow-sm:  0 1px 3px rgba(0,0,0,.3);
  --shadow-md:  0 4px 16px rgba(0,0,0,.35);
  --shadow-lg:  0 8px 32px rgba(0,0,0,.4);
  --shadow-card: 0 20px 60px rgba(79,110,247,.15), 0 4px 12px rgba(0,0,0,.3);
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans', 'Hiragino Sans', Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  transition: background var(--transition-slow), color var(--transition-slow);
  overflow-x: hidden;
}

ul { list-style: none; }
button { border: none; cursor: pointer; font-family: inherit; }
input { font-family: inherit; outline: none; }
pre {
  background: var(--bg-surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px;
  font-size: .78rem;
  overflow-x: auto;
  color: var(--text-secondary);
  white-space: pre-wrap;
}

/* ---------- Layout ---------- */
.sidebar {
  position: fixed;
  top: 0; left: 0;
  width: var(--sidebar-w);
  height: 100vh;
  background: var(--bg-sidebar);
  display: flex;
  flex-direction: column;
  gap: 0;
  overflow-y: auto;
  overflow-x: hidden;
  z-index: 200;
  transform: translateX(0);
  transition: transform var(--transition-med);
}

.main-wrapper {
  margin-left: var(--sidebar-w);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: margin-left var(--transition-med);
}

/* ---------- Sidebar ---------- */
.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 16px 16px;
  border-bottom: 1px solid rgba(255,255,255,.06);
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-icon {
  font-size: 1.6rem;
  line-height: 1;
}

.logo-name {
  display: block;
  font-size: 1.05rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: .5px;
}

.logo-sub {
  display: block;
  font-size: .65rem;
  color: var(--text-sidebar);
  letter-spacing: .3px;
}

.sidebar-close {
  background: transparent;
  color: var(--text-sidebar);
  font-size: .9rem;
  padding: 4px 6px;
  border-radius: var(--radius-sm);
  display: none;
}

/* Mode toggle inside sidebar */
.mode-toggle-box {
  padding: 14px 16px;
  border-bottom: 1px solid rgba(255,255,255,.06);
}

.toggle-label, .section-label {
  font-size: .68rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: #4a6080;
  margin-bottom: 8px;
}

.mode-toggle {
  display: flex;
  gap: 6px;
}

.mode-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 7px 6px;
  background: rgba(255,255,255,.07);
  color: var(--text-sidebar);
  border-radius: var(--radius-sm);
  font-size: .78rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

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

/* Sidebar sections */
.sidebar-section {
  padding: 14px 16px;
  border-bottom: 1px solid rgba(255,255,255,.06);
}

.category-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.cat-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--text-sidebar);
  font-size: .82rem;
  transition: all var(--transition-fast);
  user-select: none;
}

.cat-item:hover,
.cat-item.active {
  background: rgba(79,110,247,.25);
  color: #fff;
}

.cat-item .cat-name {
  display: flex;
  align-items: center;
  gap: 7px;
}

.cat-item .cat-count {
  font-size: .7rem;
  background: rgba(255,255,255,.12);
  padding: 1px 7px;
  border-radius: 20px;
  color: #7a90b0;
}

.cat-item.active .cat-count {
  background: rgba(255,255,255,.2);
  color: #fff;
}

/* Sidebar progress */
.sidebar-progress-section { }

.sidebar-progress-bar-wrap {
  background: rgba(255,255,255,.08);
  border-radius: 99px;
  height: 6px;
  overflow: hidden;
  margin-bottom: 6px;
}

.sidebar-progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-2), #34d399);
  border-radius: 99px;
  width: 0%;
  transition: width var(--transition-slow);
}

.sidebar-progress-stats {
  display: flex;
  justify-content: space-between;
  font-size: .72rem;
  color: #4a6080;
}

/* Sidebar mini stats */
.sidebar-mini-stats {
  display: flex;
  gap: 0;
  margin-top: auto;
  border-top: 1px solid rgba(255,255,255,.06);
}

.mini-stat {
  flex: 1;
  text-align: center;
  padding: 14px 4px;
}

.mini-stat-value {
  font-size: 1.2rem;
  font-weight: 700;
  color: #fff;
  line-height: 1;
}

.mini-stat-label {
  font-size: .6rem;
  color: #4a6080;
  margin-top: 3px;
  text-transform: uppercase;
  letter-spacing: .5px;
}

/* Sidebar overlay (mobile) */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: 199;
}

/* ---------- Top bar ---------- */
.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  gap: 12px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.top-bar-left {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  min-width: 0;
}

.top-bar-right {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}

/* Search */
.search-wrap {
  display: flex;
  align-items: center;
  background: var(--bg-surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-md);
  padding: 7px 12px;
  gap: 6px;
  flex: 1;
  transition: border-color var(--transition-fast);
  max-width: 420px;
}

.search-wrap:focus-within {
  border-color: var(--accent);
  background: var(--bg-surface);
}

.search-icon { font-size: .85rem; }

.search-input {
  border: none;
  background: transparent;
  font-size: .88rem;
  color: var(--text-primary);
  flex: 1;
  min-width: 0;
}

.search-input::placeholder { color: var(--text-muted); }

.search-clear {
  background: transparent;
  color: var(--text-muted);
  font-size: .75rem;
  padding: 2px 4px;
}

/* Buttons */
.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface-2);
  border: 1.5px solid var(--border);
  font-size: .95rem;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
}

.btn-with-label {
  width: auto;
  gap: 4px;
  padding: 0 10px;
  font-size: .8rem;
}

.btn-label { font-size: .75rem; font-weight: 500; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-size: .88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-nav {
  background: var(--bg-surface);
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
  padding: 10px 18px;
}

.btn-nav:hover {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
}

.btn-hard {
  background: #fff3cd;
  border: 1.5px solid #ffc107;
  color: #856404;
}

.btn-hard:hover {
  background: #ffc107;
  color: #fff;
}

.btn-learned {
  background: #d1fae5;
  border: 1.5px solid var(--accent-2);
  color: #065f46;
}

.btn-learned:hover {
  background: var(--accent-2);
  color: #fff;
}

.dark-mode .btn-hard {
  background: #3d2d00;
  border-color: #ffc107;
  color: #fbbf24;
}

.dark-mode .btn-learned {
  background: #022c22;
  border-color: var(--accent-2);
  color: #34d399;
}

.btn-ghost {
  background: transparent;
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
}

.btn-ghost:hover {
  background: var(--bg-surface);
  border-color: var(--accent);
  color: var(--accent);
}

.btn-primary {
  background: var(--accent);
  border: none;
  color: #fff;
}

.btn-primary:hover { background: var(--accent-hover); }

.btn-secondary {
  background: var(--bg-surface-2);
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ---------- Flashcard Section ---------- */
.flashcard-section {
  padding: 24px 24px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

/* Status bar */
.card-status-bar {
  width: 100%;
  max-width: 560px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.card-counter-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
}

.card-counter {
  font-size: .85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.level-badge {
  font-size: .65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .8px;
  padding: 2px 8px;
  border-radius: 99px;
  background: var(--accent-light);
  color: var(--accent);
  border: 1px solid var(--accent);
}

.level-badge.level-intermediate {
  background: #fffbeb;
  color: #b45309;
  border-color: #fbbf24;
}

.level-badge.level-advanced {
  background: #fdf2f8;
  color: #9d174d;
  border-color: #f472b6;
}

.dark-mode .level-badge.level-intermediate {
  background: #3d2d00;
  color: #fbbf24;
}

.dark-mode .level-badge.level-advanced {
  background: #3d0f25;
  color: #f472b6;
}

.card-filter-info {
  font-size: .78rem;
  color: var(--text-muted);
  font-style: italic;
  flex: 1;
  text-align: center;
}

.card-action-icons {
  display: flex;
  gap: 6px;
}

.icon-btn {
  background: transparent;
  border: 1.5px solid var(--border);
  color: var(--text-muted);
  font-size: .95rem;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.icon-btn:hover {
  border-color: var(--accent-3);
  color: var(--accent-3);
}

.fav-btn.is-fav {
  border-color: var(--accent-3);
  color: var(--accent-3);
  background: #fffbeb;
}

.dark-mode .fav-btn.is-fav {
  background: #3d2d00;
}

/* Flashcard 3D flip */
.flashcard-viewport {
  width: 100%;
  max-width: 560px;
}

.flashcard-scene {
  perspective: 1200px;
  width: 100%;
}

.flashcard {
  position: relative;
  width: 100%;
  height: 300px;
  transform-style: preserve-3d;
  transition: transform 0.55s cubic-bezier(0.45, 0.05, 0.55, 0.95);
  cursor: pointer;
}

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

.card-face {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

/* Front face */
.card-front {
  background: var(--card-front-bg);
}

.card-front .card-face-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  padding: 28px 32px;
  gap: 12px;
  position: relative;
}

.card-category-chip {
  background: rgba(255,255,255,.2);
  color: rgba(255,255,255,.9);
  font-size: .72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 4px 12px;
  border-radius: 99px;
}

.card-main-word {
  font-size: 1.9rem;
  font-weight: 700;
  color: #fff;
  text-align: center;
  line-height: 1.25;
  text-shadow: 0 2px 8px rgba(0,0,0,.15);
}

.card-flip-hint {
  position: absolute;
  bottom: 18px;
  left: 50%;
  transform: translateX(-50%);
  color: rgba(255,255,255,.65);
  font-size: .75rem;
  display: flex;
  align-items: center;
  gap: 4px;
}

.hint-icon { font-size: .85rem; }

/* Front decorative circles */
.card-front::before,
.card-front::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  background: rgba(255,255,255,.06);
  pointer-events: none;
}

.card-front::before {
  width: 200px;
  height: 200px;
  top: -60px;
  right: -60px;
}

.card-front::after {
  width: 120px;
  height: 120px;
  bottom: -30px;
  left: -20px;
}

/* Back face */
.card-back {
  background: var(--card-back-bg);
  border: 1.5px solid var(--border);
  transform: rotateY(180deg);
}

.card-back .card-face-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: 22px 28px;
  gap: 10px;
  overflow-y: auto;
  position: relative;
}

.card-translation {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1.3;
}

.card-divider {
  height: 1px;
  background: var(--border);
}

.card-example-block {
  flex: 1;
}

.example-label {
  font-size: .68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .8px;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.example-en {
  font-size: .88rem;
  color: var(--text-primary);
  line-height: 1.5;
  margin-bottom: 5px;
  font-style: italic;
}

.example-vi {
  font-size: .83rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: auto;
}

.tag-chip {
  font-size: .65rem;
  padding: 2px 8px;
  border-radius: 99px;
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 500;
}

.speak-back-btn {
  position: absolute;
  bottom: 14px;
  right: 16px;
  background: var(--bg-surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  width: 30px;
  height: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .85rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.speak-back-btn:hover {
  background: var(--accent-light);
  border-color: var(--accent);
}

/* ---------- Navigation Controls ---------- */
.nav-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  width: 100%;
  max-width: 560px;
}

.center-controls {
  display: flex;
  gap: 10px;
}

/* ---------- Action Row ---------- */
.action-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

/* ---------- Progress ---------- */
.progress-section {
  width: 100%;
  max-width: 560px;
}

.progress-track {
  background: var(--border);
  border-radius: 99px;
  height: 8px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-2), #6ee7b7);
  border-radius: 99px;
  width: 0%;
  transition: width var(--transition-slow);
}

.progress-labels {
  display: flex;
  justify-content: space-between;
  font-size: .72rem;
  color: var(--text-muted);
  margin-top: 5px;
}

/* ---------- Quiz Section ---------- */
.quiz-section {
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.hidden { display: none !important; }

.quiz-header { display: flex; flex-direction: column; gap: 10px; }

.quiz-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.quiz-title {
  font-size: 1.2rem;
  font-weight: 700;
}

.quiz-score-bar {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  font-size: .82rem;
  color: var(--text-secondary);
}

.quiz-score-item { display: flex; align-items: center; gap: 4px; }

.correct-score { color: var(--accent-2); }
.wrong-score   { color: var(--accent-4); }

.quiz-accuracy {
  margin-left: auto;
  font-weight: 700;
  color: var(--accent);
}

.quiz-card-wrap {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 640px;
  margin: 0 auto;
  width: 100%;
}

.quiz-question-card {
  background: var(--bg-surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  box-shadow: var(--shadow-md);
  text-align: center;
}

.quiz-question-label {
  font-size: .72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .8px;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.quiz-question-word {
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.quiz-question-example {
  font-size: .8rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 8px;
  line-height: 1.5;
}

.quiz-options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.quiz-option {
  background: var(--bg-surface);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  font-size: .9rem;
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  text-align: left;
  line-height: 1.4;
  transition: all var(--transition-fast);
  position: relative;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--accent-light);
  color: var(--accent);
}

.quiz-option.correct {
  border-color: var(--accent-2);
  background: #d1fae5;
  color: #065f46;
}

.quiz-option.wrong {
  border-color: var(--accent-4);
  background: #fee2e2;
  color: #991b1b;
}

.dark-mode .quiz-option.correct {
  background: #022c22;
  color: #34d399;
}

.dark-mode .quiz-option.wrong {
  background: #3b0f0f;
  color: #f87171;
}

.quiz-option:disabled { cursor: not-allowed; }

.quiz-option .opt-letter {
  display: inline-block;
  width: 22px;
  height: 22px;
  background: var(--border);
  border-radius: 50%;
  text-align: center;
  line-height: 22px;
  font-size: .72rem;
  font-weight: 700;
  margin-right: 8px;
  vertical-align: middle;
  flex-shrink: 0;
}

.quiz-option.correct .opt-letter { background: var(--accent-2); color: #fff; }
.quiz-option.wrong   .opt-letter { background: var(--accent-4); color: #fff; }

.quiz-next-row {
  max-width: 640px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  justify-content: flex-end;
}

/* ---------- Dashboard ---------- */
.dashboard {
  margin: 8px 24px 32px;
  background: var(--bg-surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.dashboard-toggle-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: transparent;
  color: var(--text-primary);
  font-size: .95rem;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
}

.dashboard-toggle-btn:hover { background: var(--bg-surface-2); }

.dashboard-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* KPI grid */
.kpi-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
  gap: 12px;
}

.kpi-card {
  background: var(--bg-surface-2);
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 16px 12px;
  text-align: center;
  transition: box-shadow var(--transition-fast);
}

.kpi-card:hover { box-shadow: var(--shadow-md); }

.kpi-icon { font-size: 1.4rem; margin-bottom: 6px; }

.kpi-value {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1;
  margin-bottom: 4px;
}

.kpi-label {
  font-size: .68rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .5px;
}

.kpi-total   { border-top: 3px solid var(--accent);   }
.kpi-learned { border-top: 3px solid var(--accent-2); }
.kpi-accuracy{ border-top: 3px solid var(--accent-5); }
.kpi-streak  { border-top: 3px solid var(--accent-3); }
.kpi-fav     { border-top: 3px solid var(--accent-3); }
.kpi-hard    { border-top: 3px solid var(--accent-4); }

/* Category breakdown */
.cat-progress-item {
  margin-bottom: 12px;
}

.cat-progress-header {
  display: flex;
  justify-content: space-between;
  font-size: .8rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.cat-progress-header strong { color: var(--text-primary); }

.cat-progress-track {
  background: var(--border);
  border-radius: 99px;
  height: 6px;
  overflow: hidden;
}

.cat-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #818cf8);
  border-radius: 99px;
  transition: width var(--transition-slow);
}

/* ---------- Guide Modal ---------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.55);
  backdrop-filter: blur(4px);
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.modal-box {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 560px;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
  animation: modalIn .25s ease;
}

@keyframes modalIn {
  from { opacity: 0; transform: scale(.95) translateY(10px); }
  to   { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
  border-bottom: 1px solid var(--border);
}

.modal-header h3 { font-size: 1.05rem; font-weight: 700; }

.modal-body {
  padding: 20px;
  overflow-y: auto;
  font-size: .88rem;
  line-height: 1.7;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.modal-body h4 {
  font-size: .88rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 8px;
}

.modal-body ul, .modal-body ol {
  padding-left: 18px;
}

.modal-body ul { list-style: disc; }
.modal-body ol { list-style: decimal; }

.modal-body li { margin-bottom: 4px; }

.modal-body code {
  background: var(--bg-surface-2);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: .82rem;
  color: var(--accent);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: #1e293b;
  color: #f1f5f9;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-size: .85rem;
  font-weight: 500;
  z-index: 999;
  opacity: 0;
  transition: all .3s ease;
  box-shadow: var(--shadow-lg);
  white-space: nowrap;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.dark-mode .toast {
  background: #f1f5f9;
  color: #1e293b;
}

/* ---------- Scrollbar ---------- */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 99px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ---------- Responsive: Tablet ---------- */
@media (max-width: 900px) {
  .btn-label { display: none; }
  .btn-with-label { width: 36px; }
}

/* ---------- Responsive: Mobile ---------- */
@media (max-width: 680px) {
  :root { --sidebar-w: 260px; }

  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-close { display: flex; }
  .sidebar-overlay.visible { display: block; }

  .main-wrapper { margin-left: 0; }

  .flashcard-section { padding: 16px 16px 12px; }

  .flashcard { height: 260px; }

  .card-main-word { font-size: 1.55rem; }
  .card-translation { font-size: 1.25rem; }

  .nav-controls { gap: 8px; }
  .btn-nav { padding: 8px 12px; font-size: .82rem; }
  .btn { padding: 9px 14px; font-size: .82rem; }

  .quiz-options-grid { grid-template-columns: 1fr; }

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

  .dashboard { margin: 8px 16px 24px; }
  .quiz-section { padding: 16px; }

  .top-bar { padding: 10px 12px; }
}

@media (max-width: 380px) {
  .card-main-word { font-size: 1.3rem; }
  .kpi-grid { grid-template-columns: repeat(2, 1fr); }
  .center-controls { gap: 6px; }
}

/* ---------- Utility ---------- */
.text-center { text-align: center; }
.mt-auto { margin-top: auto; }

/* Active favorites view highlight */
.favToggleBtn.fav-active {
  background: #fffbeb;
  border-color: var(--accent-3);
  color: var(--accent-3);
}