:root {
  --bg-color: #0b0f19;
  --card-bg: #141b2d;
  --card-border: #1e293b;
  --text-main: #f8fafc;
  --text-secondary: #94a3b8;
  --accent-bio: #10b981;
  --accent-chem: #38bdf8;
  --accent-purple: #8b5cf6;
  --success: #10b981;
  --danger: #ef4444;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
}

/* Telegram theme integration */
body.telegram-theme {
  --bg-color: var(--tg-theme-bg-color, #0b0f19);
  --card-bg: var(--tg-theme-secondary-bg-color, #141b2d);
  --text-main: var(--tg-theme-text-color, #f8fafc);
  --text-secondary: var(--tg-theme-hint-color, #94a3b8);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  justify-content: center;
}

#app {
  width: 100%;
  max-width: 520px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  padding: 16px;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0 16px 0;
  border-bottom: 1px solid var(--card-border);
  margin-bottom: 16px;
}

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

.logo-icon {
  font-size: 28px;
}

.logo-title {
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.logo-sub {
  font-size: 11px;
  color: var(--text-secondary);
}

.badge {
  font-size: 12px;
  padding: 4px 10px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  color: var(--text-secondary);
}

.badge.dev {
  background: rgba(139, 92, 246, 0.15);
  border-color: var(--accent-purple);
  color: #c084fc;
  font-weight: 600;
}

/* Views */
.view {
  display: none;
  animation: fadeIn 0.25s ease-out;
}

.view.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Hero card */
.hero-card {
  background: linear-gradient(145deg, #1e293b, #0f172a);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  text-align: center;
  margin-bottom: 20px;
}

.hero-icon {
  font-size: 36px;
  margin-bottom: 8px;
}

.hero-card h2 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 8px;
}

.hero-card p {
  font-size: 13px;
  color: var(--text-secondary);
}

/* Subject cards */
.subjects-grid {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 20px;
}

.subject-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  cursor: pointer;
  transition: transform 0.15s, border-color 0.15s;
}

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

.subject-card.bio {
  border-left: 4px solid var(--accent-bio);
}

.subject-card.chem {
  border-left: 4px solid var(--accent-chem);
}

.subject-card-icon {
  font-size: 32px;
}

.subject-card-info h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 4px;
}

.subject-card-info p {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  font-family: var(--font-mono);
  color: var(--text-secondary);
}

.tag {
  background: rgba(255, 255, 255, 0.06);
  padding: 2px 8px;
  border-radius: 4px;
}

.btn-card-action {
  align-self: flex-start;
  background: transparent;
  border: none;
  color: var(--text-main);
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
}

/* Quiz Topbar */
.quiz-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.sub-label {
  font-size: 12px;
  color: var(--text-secondary);
}

.sub-val {
  font-size: 14px;
  font-weight: 700;
}

.counter-badge {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  background: var(--card-bg);
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--card-border);
}

/* Progress track */
.progress-track {
  width: 100%;
  height: 6px;
  background: var(--card-border);
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 20px;
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-bio), var(--accent-chem));
  transition: width 0.3s ease;
}

/* Question Container */
.question-container {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 16px;
}

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

.question-num-tag {
  font-size: 12px;
  font-weight: 700;
  color: var(--accent-chem);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.timer-badge {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-secondary);
}

.question-text {
  font-size: 16px;
  font-weight: 600;
  line-height: 1.45;
}

/* Options */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.opt-btn {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  color: var(--text-main);
  font-size: 15px;
  font-weight: 500;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  transition: background 0.15s, border-color 0.15s;
}

.opt-btn:active {
  background: rgba(255, 255, 255, 0.05);
}

.opt-letter {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--text-secondary);
  font-size: 13px;
  background: rgba(255, 255, 255, 0.05);
  width: 24px;
  height: 24px;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.opt-btn.correct {
  background: rgba(16, 185, 129, 0.15);
  border-color: var(--success);
  color: #6ee7b7;
}

.opt-btn.wrong {
  background: rgba(239, 68, 68, 0.15);
  border-color: var(--danger);
  color: #fca5a5;
}

/* Result Card */
.result-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-align: center;
  margin-bottom: 20px;
}

.result-badge-icon {
  font-size: 52px;
  margin-bottom: 8px;
}

.result-card h2 {
  font-size: 22px;
  font-weight: 800;
  margin-bottom: 12px;
}

.score-display {
  margin-bottom: 8px;
}

.big-score {
  font-size: 48px;
  font-weight: 800;
  color: var(--accent-bio);
  font-family: var(--font-mono);
}

.total-score {
  font-size: 24px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.percent-tag {
  display: inline-block;
  background: rgba(16, 185, 129, 0.1);
  color: var(--accent-bio);
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 12px;
}

.res-msg {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 18px;
}

/* Buttons */
.btn-primary {
  width: 100%;
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
  border: none;
  border-radius: var(--radius-md);
  padding: 14px;
  color: #fff;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  transition: opacity 0.15s;
}

.btn-primary:active {
  opacity: 0.85;
}

.btn-secondary {
  width: 100%;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 12px;
  color: var(--text-main);
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
}

.btn-secondary:active {
  background: rgba(255, 255, 255, 0.05);
}

.action-buttons-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 16px;
}

/* Mistakes Box */
.mistakes-box {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 16px;
  margin-bottom: 16px;
  text-align: left;
}

.mistakes-header h4 {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 12px;
}

.mistakes-items {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 280px;
  overflow-y: auto;
}

.mistake-item {
  padding: 10px;
  background: rgba(0, 0, 0, 0.2);
  border-radius: var(--radius-sm);
  font-size: 13px;
  border-left: 3px solid var(--danger);
}

.mistake-q {
  font-weight: 600;
  margin-bottom: 4px;
}

.mistake-user {
  color: #fca5a5;
}

.mistake-correct {
  color: #6ee7b7;
}

/* Developer Section */
.dev-btn {
  margin-top: 8px;
  border-color: rgba(139, 92, 246, 0.4);
  color: #c084fc;
}

.dev-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.btn-icon {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  color: var(--text-main);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.stats-cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-bottom: 16px;
}

.stat-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 12px;
  text-align: center;
}

.stat-num {
  display: block;
  font-size: 20px;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--accent-chem);
}

.stat-label {
  font-size: 10px;
  color: var(--text-secondary);
}

.dev-box {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 16px;
  margin-bottom: 16px;
}

.dev-box h4 {
  font-size: 14px;
  font-weight: 700;
  margin-bottom: 6px;
}

.dev-hint {
  font-size: 11px;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

textarea {
  width: 100%;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  padding: 10px;
  font-size: 12px;
  font-family: var(--font-mono);
  resize: vertical;
  margin-bottom: 10px;
}

textarea:focus {
  outline: none;
  border-color: var(--accent-purple);
}

.hidden {
  display: none !important;
}