/* ========================================
   Viva Studio — Main Stylesheet
   ======================================== */

/* --- CSS Variables --- */
:root {
  --bg: #fafafa;
  --bg-card: #ffffff;
  --bg-hover: #f0f4f8;
  --bg-active: #e8f0fe;
  --text: #1a1a2e;
  --text-secondary: #5a5a7a;
  --text-muted: #8888a0;
  --accent: #4361ee;
  --accent-light: #e8f0fe;
  --accent-dark: #3a56d4;
  --green: #10b981;
  --green-light: #d1fae5;
  --yellow: #f59e0b;
  --yellow-light: #fef3c7;
  --red: #ef4444;
  --red-light: #fee2e2;
  --border: #e2e8f0;
  --border-light: #f1f5f9;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 16px rgba(0,0,0,0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --radius-xs: 4px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --nav-h: 56px;
  --max-w: 860px;
  --transition: 0.2s ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  min-height: 100vh;
  padding-bottom: 80px;
  overflow-x: hidden;
}

/* --- Typography --- */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.3; }
h1 { font-size: 1.75rem; }
h2 { font-size: 1.35rem; }
h3 { font-size: 1.15rem; }
h4 { font-size: 1rem; }

p { margin-bottom: 0.75rem; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  display: flex;
  align-items: center;
  padding: 0 16px;
  box-shadow: var(--shadow-sm);
}

.nav-brand {
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  white-space: nowrap;
}

.nav-brand svg { width: 24px; height: 24px; }

.nav-links {
  display: flex;
  gap: 4px;
  margin-left: auto;
}

.nav-link {
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  background: none;
  white-space: nowrap;
}

.nav-link:hover { background: var(--bg-hover); color: var(--text); }
.nav-link.active { background: var(--accent-light); color: var(--accent); font-weight: 600; }

.nav-search-btn {
  margin-left: 8px;
  padding: 8px;
  border-radius: var(--radius-sm);
  border: none;
  background: none;
  cursor: pointer;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
}

.nav-search-btn:hover { background: var(--bg-hover); color: var(--text); }

/* --- Main Content --- */
.main {
  margin-top: calc(var(--nav-h) + 16px);
  max-width: var(--max-w);
  margin-left: auto;
  margin-right: auto;
  padding: 0 16px;
}

/* --- Cards --- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
}

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

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.card-title {
  font-size: 1.1rem;
  font-weight: 700;
}

.card-subtitle {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

/* --- Course Cards --- */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 12px;
}

.course-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.course-card:hover {
  box-shadow: var(--shadow);
  border-color: var(--accent);
  transform: translateY(-1px);
}

.course-card .course-code {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.course-card .course-name {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.course-card .course-stats {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* --- Progress Bars --- */
.progress-bar {
  width: 100%;
  height: 6px;
  background: var(--border-light);
  border-radius: 3px;
  overflow: hidden;
  margin-top: 12px;
}

.progress-fill {
  height: 100%;
  border-radius: 3px;
  background: var(--accent);
  transition: width 0.4s ease;
}

.progress-fill.good { background: var(--green); }
.progress-fill.partial { background: var(--yellow); }
.progress-fill.weak { background: var(--red); }

/* --- Study View --- */
.study-nav {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  overflow-x: auto;
  padding-bottom: 8px;
  -webkit-overflow-scrolling: touch;
}

.study-nav::-webkit-scrollbar { height: 4px; }
.study-nav::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.topic-chip {
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 500;
  white-space: nowrap;
  cursor: pointer;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-secondary);
  transition: all var(--transition);
}

.topic-chip:hover { border-color: var(--accent); color: var(--accent); }
.topic-chip.active { background: var(--accent); color: white; border-color: var(--accent); }

.study-section {
  margin-bottom: 24px;
}

.study-section-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
}

.study-section-title .icon { font-size: 1rem; }

.study-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  line-height: 1.75;
}

.study-content .ipa {
  font-family: var(--font-mono);
  background: var(--bg-hover);
  padding: 1px 6px;
  border-radius: var(--radius-xs);
  font-size: 0.95em;
}

.expandable-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  background: var(--bg-hover);
  margin-bottom: 8px;
  font-weight: 600;
  transition: background var(--transition);
}

.expandable-header:hover { background: var(--accent-light); }

.expandable-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  padding: 0 16px;
}

.expandable-body.open {
  max-height: 2000px;
  padding: 12px 16px;
}

/* --- Practice View --- */
.practice-config {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 20px;
}

.config-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.config-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.config-select, .config-input {
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  background: var(--bg-card);
  color: var(--text);
  outline: none;
  transition: border-color var(--transition);
}

.config-select:focus, .config-input:focus {
  border-color: var(--accent);
}

.question-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
}

.question-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.question-badge {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.badge-course { background: var(--accent-light); color: var(--accent); }
.badge-topic { background: var(--bg-hover); color: var(--text-secondary); }
.badge-difficulty-1 { background: var(--green-light); color: var(--green); }
.badge-difficulty-2 { background: var(--yellow-light); color: var(--yellow); }
.badge-difficulty-3 { background: var(--red-light); color: var(--red); }
.badge-essential { background: #fdf4ff; color: #a855f7; }
.badge-type { background: #f0fdf4; color: #16a34a; }

.question-text {
  font-size: 1.15rem;
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: 16px;
}

.question-counter {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.answer-area {
  margin-top: 12px;
}

.answer-textarea {
  width: 100%;
  min-height: 80px;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: 0.95rem;
  resize: vertical;
  outline: none;
  transition: border-color var(--transition);
  margin-bottom: 12px;
}

.answer-textarea:focus { border-color: var(--accent); }

.answer-reveal {
  background: var(--bg-hover);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-top: 16px;
  display: none;
}

.answer-reveal.visible { display: block; }

.answer-label {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
}

.answer-direct {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 12px;
}

.answer-viva {
  margin-bottom: 12px;
  padding: 12px;
  background: var(--accent-light);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--accent);
}

.key-points {
  margin: 12px 0;
}

.key-point {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-bottom: 6px;
  font-size: 0.9rem;
}

.key-point::before {
  content: '✓';
  color: var(--green);
  font-weight: 700;
  flex-shrink: 0;
}

.answer-explanation {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.source-ref {
  margin-top: 8px;
  font-size: 0.78rem;
  color: var(--text-muted);
  font-style: italic;
}

/* --- Rating Buttons --- */
.rating-buttons {
  display: flex;
  gap: 8px;
  margin-top: 16px;
  flex-wrap: wrap;
}

.rating-btn {
  flex: 1;
  min-width: 100px;
  padding: 12px 16px;
  border: 2px solid;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  background: transparent;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.rating-btn:hover { transform: translateY(-1px); }

.btn-got-it { border-color: var(--green); color: var(--green); }
.btn-got-it:hover { background: var(--green-light); }
.btn-partly { border-color: var(--yellow); color: var(--yellow); }
.btn-partly:hover { background: var(--yellow-light); }
.btn-missed { border-color: var(--red); color: var(--red); }
.btn-missed:hover { background: var(--red-light); }

/* --- Action Buttons --- */
.btn {
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary { background: var(--accent); color: white; }
.btn-primary:hover { background: var(--accent-dark); }
.btn-secondary { background: var(--bg-hover); color: var(--text); }
.btn-secondary:hover { background: var(--border); }
.btn-outline { background: transparent; border: 1px solid var(--border); color: var(--text-secondary); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn-small { padding: 6px 12px; font-size: 0.82rem; }
.btn-full { width: 100%; justify-content: center; }

.btn-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* --- Session Summary --- */
.session-summary {
  text-align: center;
  padding: 32px 20px;
}

.session-score {
  font-size: 3rem;
  font-weight: 800;
  color: var(--accent);
  margin-bottom: 8px;
}

.session-stats {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin: 16px 0;
}

.stat-item {
  text-align: center;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
}

.stat-label {
  font-size: 0.78rem;
  color: var(--text-muted);
  text-transform: uppercase;
}

.stat-got-it .stat-value { color: var(--green); }
.stat-partly .stat-value { color: var(--yellow); }
.stat-missed .stat-value { color: var(--red); }

/* --- Review View --- */
.review-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0;
}

.review-tab {
  padding: 10px 16px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  border: none;
  background: none;
  border-bottom: 2px solid transparent;
  transition: all var(--transition);
}

.review-tab:hover { color: var(--text); }
.review-tab.active { color: var(--accent); border-bottom-color: var(--accent); font-weight: 600; }

.review-count {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 20px;
  height: 20px;
  padding: 0 6px;
  border-radius: 10px;
  background: var(--bg-hover);
  font-size: 0.72rem;
  font-weight: 700;
  margin-left: 4px;
}

/* --- Search Modal --- */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 200;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 80px;
}

.search-overlay.visible { display: flex; }

.search-box {
  width: 90%;
  max-width: 600px;
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.search-input-wrap {
  display: flex;
  align-items: center;
  padding: 16px;
  gap: 12px;
  border-bottom: 1px solid var(--border);
}

.search-input {
  flex: 1;
  border: none;
  outline: none;
  font-size: 1.1rem;
  font-family: var(--font);
  background: transparent;
  color: var(--text);
}

.search-results {
  max-height: 400px;
  overflow-y: auto;
  padding: 8px;
}

.search-result-item {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.search-result-item:hover { background: var(--bg-hover); }

.search-result-type {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.search-result-title {
  font-weight: 600;
  margin-top: 2px;
}

.search-result-context {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.search-empty {
  padding: 32px;
  text-align: center;
  color: var(--text-muted);
}

/* --- Mock Viva --- */
.viva-timer {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.3rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--text);
}

.viva-timer.warning { color: var(--yellow); }
.viva-timer.critical { color: var(--red); }

.viva-progress {
  display: flex;
  gap: 4px;
  margin: 12px 0;
}

.viva-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
  transition: background var(--transition);
}

.viva-dot.current { background: var(--accent); box-shadow: 0 0 0 3px var(--accent-light); }
.viva-dot.answered { background: var(--green); }
.viva-dot.skipped { background: var(--text-muted); }

/* --- Ask Guide Panel --- */
.guide-panel {
  position: fixed;
  right: 0;
  top: var(--nav-h);
  bottom: 0;
  width: 380px;
  max-width: 100vw;
  background: var(--bg-card);
  border-left: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  z-index: 150;
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.3s ease;
}

.guide-panel.open { transform: translateX(0); }

.guide-header {
  padding: 16px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.guide-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
}

.guide-not-connected {
  text-align: center;
  padding: 32px 16px;
  color: var(--text-muted);
}

.guide-input-wrap {
  padding: 12px;
  border-top: 1px solid var(--border);
  display: flex;
  gap: 8px;
}

.guide-input {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  outline: none;
  font-family: var(--font);
}

/* --- Bookmark & Notes --- */
.bookmark-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.2rem;
  color: var(--text-muted);
  transition: color var(--transition);
  padding: 4px;
}

.bookmark-btn:hover { color: var(--yellow); }
.bookmark-btn.bookmarked { color: var(--yellow); }

.note-input {
  width: 100%;
  min-height: 60px;
  padding: 10px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-family: var(--font);
  resize: vertical;
  outline: none;
  margin-top: 8px;
}

/* --- Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 300;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  background: var(--text);
  color: white;
  font-size: 0.88rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  animation: toastIn 0.3s ease;
}

.toast.success { background: var(--green); }
.toast.warning { background: var(--yellow); color: var(--text); }
.toast.error { background: var(--red); }

@keyframes toastIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* --- Storage Warning --- */
.storage-warning {
  background: var(--yellow-light);
  border: 1px solid var(--yellow);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  font-size: 0.85rem;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* --- Empty States --- */
.empty-state {
  text-align: center;
  padding: 48px 20px;
  color: var(--text-muted);
}

.empty-state .icon { font-size: 3rem; margin-bottom: 12px; }
.empty-state h3 { color: var(--text-secondary); margin-bottom: 8px; }

/* --- Loading --- */
.loading-spinner {
  display: inline-block;
  width: 24px;
  height: 24px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* --- Keyboard Shortcut Hint --- */
.kbd {
  display: inline-block;
  padding: 2px 6px;
  border: 1px solid var(--border);
  border-radius: var(--radius-xs);
  font-size: 0.75rem;
  font-family: var(--font-mono);
  background: var(--bg-hover);
  color: var(--text-secondary);
}

/* --- Filter Pills --- */
.filter-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
  align-items: center;
}

.filter-pill {
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 500;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.filter-pill:hover { border-color: var(--accent); color: var(--accent); }
.filter-pill.active { background: var(--accent); color: white; border-color: var(--accent); }

/* --- Responsive --- */
@media (max-width: 640px) {
  :root { --nav-h: 50px; }
  
  .nav { padding: 0 12px; }
  .nav-brand { font-size: 1rem; }
  .nav-link { padding: 6px 10px; font-size: 0.82rem; }
  
  .main { padding: 0 12px; }
  
  h1 { font-size: 1.4rem; }
  h2 { font-size: 1.15rem; }
  
  .course-grid { grid-template-columns: 1fr; }
  
  .question-text { font-size: 1.05rem; }
  
  .rating-btn { min-width: 80px; padding: 10px 12px; font-size: 0.82rem; }
  
  .guide-panel { width: 100vw; }
  
  .session-stats { gap: 16px; }
  .stat-value { font-size: 1.2rem; }
  
  .practice-config { flex-direction: column; }
  
  .search-overlay { padding-top: 60px; }
  .search-box { width: 95%; }
}

@media (max-width: 380px) {
  .nav-links { gap: 0; }
  .nav-link { padding: 6px 6px; font-size: 0.78rem; }
  .rating-buttons { flex-direction: column; }
  .rating-btn { min-width: 100%; }
}

/* --- Print --- */
@media print {
  .nav, .guide-panel, .toast-container { display: none !important; }
  .main { margin-top: 0; }
  body { background: white; }
}

/* --- Accessibility --- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* --- Scrollbar --- */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* --- Selection --- */
::selection { background: var(--accent-light); color: var(--accent-dark); }