/* ===== 设计变量 ===== */
:root {
  --color-bg: #f0fdf4;
  --color-bg-dark: #dcfce7;
  --color-primary: #15803d;
  --color-primary-dark: #14532d;
  --color-primary-light: #22c55e;
  --color-accent: #22c55e;
  --color-card: #ffffff;
  --color-gold: #d97706;
  --color-error: #dc2626;
  --color-text: #1e293b;
  --color-muted: #64748b;
  --shadow-green: rgba(21, 128, 61, 0.12);
  --shadow-green-lg: rgba(21, 128, 61, 0.2);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0a1f14;
    --color-bg-dark: #0f2918;
    --color-primary: #22c55e;
    --color-primary-dark: #15803d;
    --color-accent: #4ade80;
    --color-card: #14261c;
    --color-text: #f1f5f9;
    --color-muted: #94a3b8;
    --shadow-green: rgba(34, 197, 94, 0.15);
    --shadow-green-lg: rgba(34, 197, 94, 0.25);
  }
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow-x: hidden;
}

body {
  background: var(--color-bg);
  background-image:
    radial-gradient(circle at 20% 80%, rgba(34, 197, 94, 0.05) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(21, 128, 61, 0.05) 0%, transparent 50%);
  color: var(--color-text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

@supports (padding-top: env(safe-area-inset-top)) {
  .safe-area-top { padding-top: env(safe-area-inset-top); }
  .safe-area-bottom { padding-bottom: env(safe-area-inset-bottom); }
}

.mahjong-tile {
  position: relative;
  touch-action: manipulation;
  user-select: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  background: linear-gradient(145deg, #fffef7 0%, #f5f0e1 50%, #e8e0c8 100%);
  box-shadow:
    0 2px 4px rgba(0, 0, 0, 0.1),
    inset 0 1px 0 rgba(255, 255, 255, 0.8),
    inset 0 -1px 0 rgba(0, 0, 0, 0.05);
}

.mahjong-tile:active {
  transform: scale(0.95) translateY(2px);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.15);
}

.mahjong-tile img {
  filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.1));
}

.mahjong-tile--graphic {
  background: transparent;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12);
}

.mahjong-hand {
  background: linear-gradient(135deg, #166534 0%, #14532d 50%, #0f4224 100%);
  box-shadow:
    inset 0 2px 10px rgba(0, 0, 0, 0.3),
    0 4px 20px rgba(21, 128, 61, 0.3);
  position: relative;
  overflow: hidden;
}

.mahjong-hand::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  pointer-events: none;
}

.hand-area-mini {
  background: linear-gradient(135deg, #166534 0%, #14532d 100%);
  border-radius: 8px;
}

.tile-wrapper {
  animation: tileAppear 0.3s ease backwards;
}

.tile-wrapper:nth-child(1) { animation-delay: 0.02s; }
.tile-wrapper:nth-child(2) { animation-delay: 0.04s; }
.tile-wrapper:nth-child(3) { animation-delay: 0.06s; }
.tile-wrapper:nth-child(4) { animation-delay: 0.08s; }
.tile-wrapper:nth-child(5) { animation-delay: 0.10s; }
.tile-wrapper:nth-child(6) { animation-delay: 0.12s; }
.tile-wrapper:nth-child(7) { animation-delay: 0.14s; }
.tile-wrapper:nth-child(8) { animation-delay: 0.16s; }
.tile-wrapper:nth-child(9) { animation-delay: 0.18s; }
.tile-wrapper:nth-child(10) { animation-delay: 0.20s; }
.tile-wrapper:nth-child(11) { animation-delay: 0.22s; }
.tile-wrapper:nth-child(12) { animation-delay: 0.24s; }
.tile-wrapper:nth-child(13) { animation-delay: 0.26s; }
.tile-wrapper:nth-child(14) { animation-delay: 0.28s; }

@keyframes tileAppear {
  from { opacity: 0; transform: translateY(10px) scale(0.9); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.option-card {
  background: var(--color-card);
  border-radius: 12px;
  box-shadow: 0 2px 8px var(--shadow-green);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  border: 2px solid transparent;
  cursor: pointer;
}

.option-card:hover:not(.selected):not(.correct):not(.wrong) {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px var(--shadow-green-lg);
  border-color: var(--color-primary-light);
}

.option-card.selected {
  background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px var(--shadow-green-lg);
}

.option-card.correct {
  background: linear-gradient(135deg, #dcfce7 0%, #bbf7d0 100%);
  border-color: var(--color-accent);
  animation: correctPulse 0.5s ease;
}

.option-card.wrong {
  background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
  border-color: var(--color-error);
  animation: wrongShake 0.4s ease;
}

@keyframes correctPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

@keyframes wrongShake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-5px); }
  40%, 80% { transform: translateX(5px); }
}

.stats-panel {
  background: var(--color-card);
  border-radius: 16px;
  box-shadow: 0 4px 20px var(--shadow-green);
}

.stat-item { position: relative; }
.stat-item .stat-value { font-variant-numeric: tabular-nums; }
.stat-item.highlight {
  background: linear-gradient(135deg, rgba(217, 119, 6, 0.1) 0%, rgba(251, 191, 36, 0.05) 100%);
  border-radius: 8px;
}

.streak-number {
  animation: streakPulse 1s ease infinite;
  color: var(--color-gold);
}

@keyframes streakPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: white;
  font-weight: 600;
  border-radius: 12px;
  border: none;
  box-shadow: 0 4px 15px var(--shadow-green-lg);
  transition: all 0.2s ease;
  cursor: pointer;
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px var(--shadow-green-lg);
}

.btn-primary:active:not(:disabled) { transform: translateY(0); }

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  box-shadow: none;
}

.btn-secondary {
  background: var(--color-card);
  color: var(--color-muted);
  font-weight: 500;
  border-radius: 12px;
  border: none;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  transition: all 0.2s ease;
  cursor: pointer;
}

.btn-secondary:hover { background: var(--color-bg-dark); }

.answer-feedback {
  animation: feedbackAppear 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  backdrop-filter: blur(8px);
}

@keyframes feedbackAppear {
  from { opacity: 0; transform: translate(-50%, -50%) scale(0.5); }
  to { opacity: 1; transform: translate(-50%, -50%) scale(1); }
}

.question-card { animation: slideUp 0.4s ease; }

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.explanation-card {
  background: linear-gradient(135deg, #fffbeb 0%, #fef3c7 100%);
  border: 1px solid rgba(217, 119, 6, 0.2);
  border-radius: 12px;
  animation: fadeSlideIn 0.3s ease;
}

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

.loading-spinner {
  border: 3px solid var(--color-bg-dark);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

.boot-loading,
.question-loading-panel {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 24px;
  background: var(--color-bg);
  color: var(--color-muted);
  text-align: center;
}

.question-loading-panel {
  min-height: 220px;
}

.boot-spinner,
.question-loading-panel .loading-spinner {
  width: 48px;
  height: 48px;
}

.load-bar-track {
  width: min(280px, 80vw);
  height: 8px;
  background: var(--color-bg-dark);
  border-radius: 999px;
  overflow: hidden;
}

.load-bar-fill {
  height: 100%;
  width: 8%;
  background: var(--color-primary);
  border-radius: 999px;
  transition: width 0.25s ease;
}

.load-error-panel {
  min-height: 220px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 24px;
  text-align: center;
  color: var(--color-muted);
}

.load-error-panel button {
  margin-top: 8px;
  padding: 10px 20px;
  border: none;
  border-radius: 12px;
  background: var(--color-primary);
  color: #fff;
  font-size: 14px;
  cursor: pointer;
}

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

.page-enter { animation: pageEnter 0.4s ease; }

@keyframes pageEnter {
  from { opacity: 0; transform: translateY(15px); }
  to { opacity: 1; transform: translateY(0); }
}

.menu-panel {
  background: var(--color-card);
  box-shadow: -4px 0 30px rgba(0, 0, 0, 0.15);
}

::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--shadow-green-lg);
  border-radius: 2px;
}

.navbar-gradient {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  box-shadow: 0 4px 20px var(--shadow-green-lg);
}

.progress-ring { transform: rotate(-90deg); }
.progress-ring-circle { transition: stroke-dashoffset 0.5s ease; }

#float-ad-btn {
  animation: floatBtnPulse 2s ease-in-out infinite;
  touch-action: manipulation;
}

@keyframes floatBtnPulse {
  0%, 100% {
    transform: scale(1);
    box-shadow: 0 4px 20px rgba(251, 191, 36, 0.4);
  }
  50% {
    transform: scale(1.05);
    box-shadow: 0 6px 25px rgba(251, 191, 36, 0.6);
  }
}

#float-ad-btn:hover { animation: none; }

#ad-modal > div {
  animation: adModalAppear 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes adModalAppear {
  from { opacity: 0; transform: scale(0.9) translateY(20px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}

.hidden { display: none !important; }