:root {
  --bg-color: var(--tg-theme-bg-color, #0f172a);
  --secondary-bg: var(--tg-theme-secondary-bg-color, #1e293b);
  --card-bg: rgba(30, 41, 59, 0.75);
  --card-border: rgba(255, 255, 255, 0.08);
  --text-color: var(--tg-theme-text-color, #f8fafc);
  --hint-color: var(--tg-theme-hint-color, #94a3b8);
  --link-color: var(--tg-theme-link-color, #38bdf8);
  --button-color: var(--tg-theme-button-color, #3b82f6);
  --button-text: var(--tg-theme-button-text-color, #ffffff);
  --accent-color: #6366f1;
  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #3b82f6 50%, #06b6d4 100%);
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-card: 0 4px 20px -2px rgba(0, 0, 0, 0.25);
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: light) {
  :root:not(.dark) {
    --bg-color: var(--tg-theme-bg-color, #f8fafc);
    --secondary-bg: var(--tg-theme-secondary-bg-color, #f1f5f9);
    --card-bg: rgba(255, 255, 255, 0.85);
    --card-border: rgba(0, 0, 0, 0.08);
    --text-color: var(--tg-theme-text-color, #0f172a);
    --hint-color: var(--tg-theme-hint-color, #64748b);
    --shadow-card: 0 4px 20px -2px rgba(0, 0, 0, 0.06);
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-color);
  min-height: 100vh;
  padding-bottom: 80px;
  line-height: 1.5;
  transition: background-color 0.2s ease, color 0.2s ease;
}

/* Container */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 16px;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  margin-bottom: 16px;
  box-shadow: var(--shadow-card);
}

.user-profile {
  display: flex;
  align-items: center;
  gap: 12px;
}

.user-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--accent-gradient);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.2rem;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.35);
}

.user-meta h2 {
  font-size: 1.05rem;
  font-weight: 700;
  line-height: 1.2;
}

.user-meta .username {
  font-size: 0.8rem;
  color: var(--hint-color);
}

.header-badges {
  display: flex;
  gap: 8px;
  align-items: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 600;
}

.badge-streak {
  background: rgba(245, 158, 11, 0.15);
  color: #f59e0b;
  border: 1px solid rgba(245, 158, 11, 0.3);
}

/* Stats Overview */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-bottom: 16px;
}

@media (max-width: 600px) {
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.stat-card {
  background: var(--card-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  text-align: center;
  box-shadow: var(--shadow-card);
  transition: transform 0.15s ease;
}

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

.stat-card .stat-value {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--text-color);
  margin-bottom: 2px;
}

.stat-card .stat-label {
  font-size: 0.75rem;
  color: var(--hint-color);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-weight: 600;
}

.stat-card.due .stat-value { color: #f43f5e; }
.stat-card.learning .stat-value { color: #3b82f6; }
.stat-card.mastered .stat-value { color: #10b981; }

/* Filter & Search Bar */
.controls-panel {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 14px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.search-box {
  position: relative;
  width: 100%;
}

.search-box input {
  width: 100%;
  padding: 12px 40px 12px 38px;
  background: var(--secondary-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  color: var(--text-color);
  font-size: 0.95rem;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.search-box input:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--hint-color);
  pointer-events: none;
}

.search-clear {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: var(--hint-color);
  cursor: pointer;
  display: none;
  font-size: 1.1rem;
}

.filters-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
}

.filter-chips {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.chip {
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 600;
  background: var(--secondary-bg);
  color: var(--hint-color);
  border: 1px solid var(--card-border);
  cursor: pointer;
  transition: all 0.2s ease;
}

.chip.active {
  background: var(--button-color);
  color: var(--button-text);
  border-color: var(--button-color);
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.35);
}

.sort-select {
  padding: 6px 12px;
  background: var(--secondary-bg);
  color: var(--text-color);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 500;
  outline: none;
  cursor: pointer;
}

/* Words List / Cards */
.words-container {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.word-card {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 16px;
  box-shadow: var(--shadow-card);
  transition: transform 0.15s ease, border-color 0.2s ease;
  position: relative;
  overflow: hidden;
}

.word-card:hover {
  border-color: rgba(99, 102, 241, 0.4);
}

.word-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 6px;
}

.word-title-group {
  display: flex;
  align-items: baseline;
  gap: 8px;
  flex-wrap: wrap;
}

.word-canonical {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-color);
  letter-spacing: -0.2px;
}

.word-pos {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 6px;
  background: rgba(99, 102, 241, 0.15);
  color: #818cf8;
  text-transform: lowercase;
}

.word-transcription {
  font-family: "Lucida Sans Unicode", "Segoe UI", sans-serif;
  font-size: 0.9rem;
  color: var(--hint-color);
  letter-spacing: 0.5px;
}

.audio-btn {
  background: rgba(59, 130, 246, 0.15);
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: var(--button-color);
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.15s ease;
  flex-shrink: 0;
}

.audio-btn:hover, .audio-btn:active {
  background: var(--button-color);
  color: #fff;
  transform: scale(1.06);
}

.audio-btn.playing {
  animation: pulse-audio 1s infinite alternate;
}

@keyframes pulse-audio {
  from { transform: scale(1); }
  to { transform: scale(1.12); }
}

.word-translation {
  font-size: 1.05rem;
  font-weight: 600;
  color: #38bdf8;
  margin-bottom: 8px;
}

/* Examples */
.word-examples {
  margin: 8px 0;
  padding: 8px 12px;
  background: var(--secondary-bg);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--accent-color);
  font-size: 0.88rem;
}

.example-en {
  color: var(--text-color);
  margin-bottom: 2px;
}

.example-en b, .example-en strong {
  color: #a5b4fc;
}

.example-ru {
  color: var(--hint-color);
  font-size: 0.82rem;
}

/* Synonyms & Collocations */
.tags-row {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 8px;
}

.tag-pill {
  font-size: 0.72rem;
  padding: 2px 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.06);
  color: var(--hint-color);
}

/* SM-2 Retention Meta */
.word-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--card-border);
  font-size: 0.78rem;
}

.sm2-status {
  display: flex;
  align-items: center;
  gap: 6px;
}

.retention-bars {
  display: flex;
  gap: 3px;
}

.retention-bar {
  width: 6px;
  height: 12px;
  border-radius: 2px;
  background: rgba(255, 255, 255, 0.12);
}

.retention-bar.filled {
  background: var(--success-color);
}

.retention-bar.filled.medium {
  background: var(--warning-color);
}

.retention-bar.filled.low {
  background: #f43f5e;
}

.next-review-badge {
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 6px;
}

.next-review-badge.due {
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
}

.next-review-badge.soon {
  background: rgba(245, 158, 11, 0.15);
  color: #fbbf24;
}

.next-review-badge.future {
  background: rgba(16, 185, 129, 0.15);
  color: #34d399;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 48px 16px;
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  border: 1px dashed var(--card-border);
}

.empty-state-icon {
  font-size: 3rem;
  margin-bottom: 12px;
}

.empty-state h3 {
  font-size: 1.15rem;
  margin-bottom: 6px;
}

.empty-state p {
  color: var(--hint-color);
  font-size: 0.9rem;
  max-width: 400px;
  margin: 0 auto;
}

/* Floating Bottom Action */
.bottom-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 12px 16px;
  background: var(--card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-top: 1px solid var(--card-border);
  display: flex;
  justify-content: center;
  z-index: 100;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background: var(--accent-gradient);
  color: #ffffff;
  border: none;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(99, 102, 241, 0.4);
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  max-width: 500px;
  width: 100%;
}

.btn-primary:active {
  transform: scale(0.98);
}

/* Loading Spinner */
.spinner-container {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 40px;
}

.spinner {
  width: 36px;
  height: 36px;
  border: 3px solid rgba(255, 255, 255, 0.1);
  border-top-color: var(--button-color);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Login Fallback Modal (for direct desktop browser access) */
.auth-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(10px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999;
  padding: 16px;
}

.auth-modal {
  background: var(--secondary-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  max-width: 420px;
  width: 100%;
  text-align: center;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
}

.auth-modal h2 {
  font-size: 1.3rem;
  margin-bottom: 12px;
}

.auth-modal p {
  color: var(--hint-color);
  font-size: 0.9rem;
  margin-bottom: 20px;
  line-height: 1.5;
}