/* ============================================================
   Tango Puzzle - 样式
   设计基调: 呼吸感留白 / 日月双色 (太阳橙 + 月亮蓝) / 圆角卡片
   ============================================================ */
:root {
  --sun: #f6a821;
  --moon: #5b7dd8;
  --ink: #23262f;
  --ink-soft: #5b6070;
  --bg: #f7f6f2;
  --card: #ffffff;
  --line: #e6e3da;
  --error: #e2574c;
  --radius: 14px;
  font-size: 16px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}
a { color: var(--moon); }

/* ---------- 顶部 ---------- */
header {
  max-width: 960px;
  margin: 0 auto;
  padding: 18px 20px 4px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}
.logo {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  text-decoration: none;
  color: var(--ink);
}
.logo .sun-dot { color: var(--sun); }
.logo .moon-dot { color: var(--moon); }
nav a {
  margin-left: 18px;
  text-decoration: none;
  color: var(--ink-soft);
  font-size: 0.95rem;
}
nav a:hover { color: var(--ink); }

/* ---------- Hero ---------- */
.hero {
  max-width: 960px;
  margin: 0 auto;
  padding: 14px 20px 4px;
  text-align: center;
}
.hero h1 {
  font-size: clamp(1.4rem, 3.2vw, 2rem);
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}
.hero p {
  color: var(--ink-soft);
  max-width: 620px;
  margin: 0 auto;
}

/* ---------- 游戏区 ---------- */
.game-wrap {
  max-width: 960px;
  margin: 14px auto 0;
  padding: 0 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 12px;
}
.toolbar select, .toolbar button {
  font: inherit;
  padding: 9px 16px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
  transition: border-color .15s, transform .1s;
}
.toolbar button:hover, .toolbar select:hover { border-color: var(--moon); }
.toolbar button:active { transform: scale(.96); }
.toolbar .primary {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
}
.timer {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  padding: 9px 14px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  min-width: 76px;
  text-align: center;
}

/* 棋盘 */
#board {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 0;
  /* 关键: 同时受宽度和视口高度约束,保证棋盘在笔记本首屏完整可见 */
  width: min(92vw, 52vh, 460px);
  aspect-ratio: 1;
  background: var(--card);
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  overflow: visible;
  padding: 4px;
}
#board.solved { border-color: var(--sun); box-shadow: 0 0 0 4px rgba(246,168,33,.25); }
.cell {
  position: relative;
  border: 1px solid var(--line);
  background: var(--card);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}
.cell svg { width: 68%; height: 68%; pointer-events: none; }
.cell.locked { background: #f1efe9; cursor: default; }
.cell.error { background: rgba(226,87,76,.14); }
.cell.error svg { filter: drop-shadow(0 0 2px rgba(226,87,76,.7)); }
.cell.hinted { animation: pop .3s ease; }
@keyframes pop { 50% { transform: scale(1.15); } }

/* 边约束标记 (= / ×) */
.edge {
  position: absolute;
  z-index: 2;
  width: 18px;
  height: 18px;
  line-height: 16px;
  text-align: center;
  font-size: 13px;
  font-weight: 700;
  background: var(--ink);
  color: #fff;
  border-radius: 50%;
  pointer-events: none;
}
.edge-right { right: -10px; top: 50%; transform: translateY(-50%); }
.edge-down { bottom: -10px; left: 50%; transform: translateX(-50%); }

.board-tip {
  margin-top: 14px;
  color: var(--ink-soft);
  font-size: 0.88rem;
  text-align: center;
}

/* 胜利弹窗 */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(35,38,47,.45);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 50;
  padding: 20px;
}
.modal.show { display: flex; }
.modal-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 36px 40px;
  text-align: center;
  max-width: 340px;
  width: 100%;
  box-shadow: 0 20px 60px rgba(0,0,0,.2);
}
.modal-card h2 { margin-bottom: 8px; }
.modal-card p { color: var(--ink-soft); margin-bottom: 20px; }
.modal-card button {
  font: inherit;
  padding: 11px 26px;
  border-radius: 10px;
  border: none;
  background: var(--sun);
  color: #fff;
  font-weight: 600;
  cursor: pointer;
}

/* ---------- 内容区 ---------- */
main.content {
  max-width: 760px;
  margin: 0 auto;
  padding: 30px 20px 10px;
}
section { margin-bottom: 46px; }
section h2 {
  font-size: 1.45rem;
  margin-bottom: 14px;
  letter-spacing: -0.01em;
}
section h3 { font-size: 1.08rem; margin: 18px 0 6px; }
section p, section li { color: var(--ink-soft); }
section ul, section ol { padding-left: 22px; margin: 8px 0; }
section li { margin-bottom: 6px; }
.rule-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 14px;
  margin-top: 16px;
}
.rule-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
}
.rule-card strong { display: block; margin-bottom: 6px; color: var(--ink); }
.rule-card span { font-size: 0.92rem; color: var(--ink-soft); }

/* FAQ */
details {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 18px;
  margin-bottom: 10px;
}
details summary { cursor: pointer; font-weight: 600; color: var(--ink); }
details p { margin-top: 10px; }

/* ---------- 页脚 ---------- */
footer {
  border-top: 1px solid var(--line);
  margin-top: 30px;
  padding: 26px 20px 40px;
  text-align: center;
  color: var(--ink-soft);
  font-size: 0.85rem;
}
footer p { max-width: 640px; margin: 0 auto 8px; }

@media (max-width: 520px) {
  nav a { margin-left: 12px; font-size: 0.88rem; }
  .modal-card { padding: 28px 24px; }
}