:root {
  --primary: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;
  --primary-bg: #eef2ff;
  --success: #10b981;
  --success-bg: #d1fae5;
  --danger: #ef4444;
  --danger-bg: #fee2e2;
  --warning: #f59e0b;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-500: #6b7280;
  --gray-700: #374151;
  --gray-900: #111827;
  --r: 16px;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans", "Microsoft YaHei", sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  min-height: 100dvh;
  line-height: 1.5;
  color: var(--gray-700);
  -webkit-tap-highlight-color: transparent;
  padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
}

.container {
  max-width: 600px;
  margin: 0 auto;
  padding: 16px;
  min-height: 100vh;
  min-height: 100dvh;
}

/* Screens */
.screen {
  display: flex;
  flex-direction: column;
  gap: 20px;
  animation: fadeIn 0.3s ease;
}

.hide {
  display: none !important;
}

/* ==================== START SCREEN ==================== */
.start-hero {
  text-align: center;
  padding: 40px 20px 20px;
}

.start-icon {
  font-size: 80px;
  font-weight: 900;
  background: linear-gradient(135deg, #fff, rgba(255,255,255,0.8));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: 0 4px 20px rgba(0,0,0,0.1);
  margin-bottom: 12px;
}

.start-hero h1 {
  font-size: 2rem;
  font-weight: 800;
  color: white;
  margin-bottom: 8px;
  text-shadow: 0 2px 10px rgba(0,0,0,0.15);
}

.start-desc {
  font-size: 1rem;
  color: rgba(255,255,255,0.85);
}

/* Start Button */
.btn-start {
  display: block;
  width: 100%;
  padding: 20px 32px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary-dark);
  background: linear-gradient(135deg, #fff, #f0f4ff);
  border: none;
  border-radius: 16px;
  cursor: pointer;
  box-shadow: 0 8px 30px rgba(0,0,0,0.2);
  transition: all 0.2s ease;
  touch-action: manipulation;
}

.btn-start:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.25);
}

.btn-start:active {
  transform: translateY(0);
}

.start-stats {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
}

.start-footer {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
  padding-bottom: 20px;
}

/* ==================== QUIZ SCREEN ==================== */
.quiz-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: rgba(255,255,255,0.95);
  border-radius: 16px;
  box-shadow: var(--shadow);
}

.quiz-progress {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 10px;
}

.progress-bar {
  flex: 1;
  height: 8px;
  background: var(--gray-200);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  border-radius: 4px;
  transition: width 0.3s ease;
  width: 0%;
}

.progress-text {
  font-size: 0.875rem;
  color: var(--gray-500);
  white-space: nowrap;
}

.progress-text b {
  color: var(--gray-900);
}

.quiz-stats {
  display: flex;
  gap: 8px;
}

.stat {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 32px;
  height: 32px;
  padding: 0 8px;
  font-size: 0.875rem;
  font-weight: 700;
  border-radius: 8px;
}

.stat.ok {
  background: var(--success-bg);
  color: #059669;
}

.stat.ng {
  background: var(--danger-bg);
  color: #dc2626;
}

.stat.streak {
  background: #fef3c7;
  color: #d97706;
}

.stat.streak::before {
  content: "🔥";
  margin-right: 2px;
  font-size: 0.75rem;
}

.stat.time {
  background: #e0e7ff;
  color: #4338ca;
}

.stat.time::before {
  content: "⏱";
  margin-right: 3px;
  font-size: 0.75rem;
}

.stat.acc {
  background: #dbeafe;
  color: #1d4ed8;
}

.stat.round {
  background: #f3e8ff;
  color: #7c3aed;
}

.btn-back {
  padding: 8px 12px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--gray-500);
  background: var(--gray-100);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-back:hover {
  background: var(--gray-200);
  color: var(--gray-700);
}

/* Quiz Card */
.quiz-card {
  background: white;
  padding: 24px;
}

.quiz-actions {
  display: flex;
  gap: 12px;
  margin-top: 20px;
}

.btn-next {
  flex: 1;
}

/* ==================== CARDS ==================== */
.card {
  background: rgba(255,255,255,0.95);
  border: none;
  border-radius: var(--r);
  padding: 16px;
  box-shadow: var(--shadow);
}

/* Layout */
.row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.wrap {
  flex-wrap: wrap;
}

.grid2 {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

@media (min-width: 500px) {
  .grid2 {
    grid-template-columns: 1fr 1fr;
  }
}

/* Pills */
.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.875rem;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.9);
  border: 1px solid rgba(255,255,255,0.5);
  color: var(--gray-700);
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.pill b {
  font-weight: 700;
  color: var(--gray-900);
}

.pill.ok {
  background: var(--success-bg);
  border-color: #a7f3d0;
  color: #065f46;
}

.pill.ng {
  background: var(--danger-bg);
  border-color: #fecaca;
  color: #991b1b;
}

/* Labels */
.label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--gray-700);
  margin-bottom: 8px;
}

/* Checkboxes */
.checks {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chk {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  border: 1px solid var(--gray-200);
  border-radius: 999px;
  background: white;
  font-size: 0.875rem;
  cursor: pointer;
  user-select: none;
  transition: all 0.15s ease;
}

.chk:hover {
  border-color: var(--primary-light);
  background: var(--primary-bg);
}

.chk:has(input:checked) {
  border-color: var(--primary);
  background: var(--primary-bg);
  color: var(--primary);
}

.chk input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--primary);
  cursor: pointer;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 16px;
  font-size: 0.9375rem;
  font-weight: 500;
  border: 1px solid var(--gray-300);
  border-radius: 12px;
  background: white;
  color: var(--gray-700);
  cursor: pointer;
  transition: all 0.15s ease;
  touch-action: manipulation;
  white-space: nowrap;
}

.btn:hover {
  background: var(--gray-50);
  border-color: var(--gray-400);
}

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

.btn.primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  border: none;
  color: white;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.btn.primary:hover {
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn.danger {
  background: var(--danger-bg);
  border-color: #fecaca;
  color: #dc2626;
}

.btn.danger:hover {
  background: #fecaca;
}

/* Select & Input */
select, input[type="number"], input[type="text"] {
  padding: 10px 14px;
  font-size: 0.9375rem;
  border: 1px solid var(--gray-300);
  border-radius: 10px;
  background: white;
  color: var(--gray-700);
  outline: none;
  transition: all 0.15s ease;
}

select:focus, input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

input[type="number"] {
  width: 80px;
}

/* Quiz Content */
.q {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--gray-900);
  padding: 8px 0;
  cursor: pointer;
  user-select: none;
  line-height: 1.6;
}

.q .big {
  display: inline-block;
  font-size: 3rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary), #a855f7);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin: 0 6px;
  vertical-align: middle;
}

.meaning {
  font-size: 0.9375rem;
  color: var(--gray-500);
  margin-top: 4px;
}

/* Options Grid */
.opts {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 20px;
}

@media (max-width: 360px) {
  .opts {
    grid-template-columns: 1fr;
  }
}

.opt {
  padding: 18px 14px;
  border: 2px solid var(--gray-200);
  border-radius: 16px;
  background: white;
  text-align: center;
  cursor: pointer;
  user-select: none;
  transition: all 0.15s ease;
}

.opt:hover {
  border-color: var(--primary-light);
  background: var(--primary-bg);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.opt:active {
  transform: translateY(0);
}

.opt .jp {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--gray-900);
}

.opt .rm {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--gray-700);
}

/* Input Mode */
#inputWrap {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
  align-items: center;
}

#inputWrap input[type="text"] {
  flex: 1;
  min-width: 160px;
  font-size: 1.125rem;
  padding: 14px 18px;
}

/* Result */
.result {
  margin-top: 16px;
  padding: 14px 18px;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 500;
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
}

.result:empty {
  display: none;
}

/* Tips */
.muted {
  font-size: 0.875rem;
  color: var(--gray-500);
  margin-top: 8px;
}

/* Mobile */
@media (max-width: 480px) {
  .container {
    padding: 12px;
  }

  .start-hero {
    padding: 30px 16px 16px;
  }

  .start-icon {
    font-size: 64px;
  }

  .start-hero h1 {
    font-size: 1.75rem;
  }

  .btn-start {
    padding: 18px 28px;
    font-size: 1.125rem;
  }

  .card {
    padding: 14px;
  }

  .quiz-header {
    padding: 10px 12px;
    gap: 8px;
  }

  .quiz-card {
    padding: 18px;
  }

  .q {
    font-size: 1.1rem;
  }

  .q .big {
    font-size: 2.5rem;
  }

  .opt {
    padding: 14px 10px;
  }

  .opt .jp {
    font-size: 1.875rem;
  }

  .chk {
    padding: 6px 10px;
    font-size: 0.8125rem;
  }

  .pill {
    font-size: 0.8125rem;
    padding: 6px 10px;
  }
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255,255,255,0.3);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255,255,255,0.5);
}