*, *::before, *::after { box-sizing: border-box; }

:root {
  --bg-0: #060d0a;
  --bg-1: #0a1612;
  --surface: rgba(255, 255, 255, .045);
  --surface-2: rgba(255, 255, 255, .08);
  --border: rgba(255, 255, 255, .1);
  --border-soft: rgba(255, 255, 255, .06);
  --text: #eef4ef;
  --muted: #9db1a6;
  --jade: #34d399;
  --jade-deep: #0f9d6b;
  --gold: #fbbf24;
  --gold-soft: #fde68a;
  --danger: #f87171;
  --radius: 16px;
  --radius-lg: 22px;
  --shadow: 0 18px 44px rgba(0, 0, 0, .42);
}

html, body { height: 100%; }

body {
  margin: 0;
  min-width: 320px;
  color: var(--text);
  font: 16px/1.6 "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
  background:
    radial-gradient(1100px 520px at 78% -8%, rgba(52, 211, 153, .16), transparent 60%),
    radial-gradient(880px 480px at 8% 4%, rgba(251, 191, 36, .1), transparent 58%),
    linear-gradient(160deg, #04100b 0%, var(--bg-0) 46%, #0b1d15 100%);
  overflow: hidden;
}

button, select, input { font: inherit; color: inherit; }

a { color: var(--jade); text-decoration: none; }
a:hover { color: var(--gold-soft); }
.foot a { color: inherit; }
.foot a:hover { color: var(--text); }

.app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
}

/* ===== 顶栏 ===== */
.topbar {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: calc(12px + env(safe-area-inset-top)) 20px 12px;
  background: linear-gradient(120deg, rgba(6, 13, 10, .92), rgba(15, 41, 28, .82));
  border-bottom: 1px solid var(--border-soft);
  backdrop-filter: blur(10px);
}

.logo { display: flex; flex: 0 0 auto; filter: drop-shadow(0 4px 10px rgba(0, 0, 0, .5)); }

.topbar__text { flex: 1 1 auto; min-width: 0; }

.topbar__text h1 {
  margin: 0;
  font-size: clamp(19px, 2.6vw, 28px);
  letter-spacing: .04em;
  line-height: 1.15;
}

.topbar__text h2 {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: clamp(14px, 1.5vw, 16px);
  font-weight: 500;
}

.topbar__diff { display: none; }

/* ===== AI 难度卡片（侧边栏） ===== */
.card--diff select {
  width: 100%;
  margin-top: 8px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #0c1d15;
  cursor: pointer;
  font-size: 14px;
}

/* ===== 移动端 AI 难度行（board 区域内） ===== */
.board__diff-bar {
  display: none;
  width: min(100%, 600px);
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border: 1px solid var(--border-soft);
  border-radius: 12px;
  background: var(--surface);
}

.board__diff-bar label {
  color: var(--muted);
  font-size: 14px;
  flex-shrink: 0;
}

.board__diff-bar select {
  flex: 1;
  padding: 7px 10px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #0c1d15;
  font-size: 14px;
  cursor: pointer;
}

/* ===== 广告位（纯 CSS 控制显隐） ===== */
.ad-slot { display: none; }
.ad-slot:not(:empty) {
  flex: 0 0 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 56px;
  max-height: 56px;
  margin: 10px 20px 0;
  color: var(--muted);
  font-size: 14px;
  border: 1px dashed var(--border);
  border-radius: 12px;
  background: rgba(255, 255, 255, .035);
}

/* ===== 主舞台 ===== */
.stage {
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  gap: 18px;
  padding: 14px 20px 16px;
  overflow: hidden;
}

.board {
  flex: 2 1 0;
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.scoreboard {
  width: min(100%, 600px);
  display: flex;
  align-items: stretch;
  gap: 10px;
}

.score {
  flex: 1 1 0;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 14px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
  font-size: 14px;
}

.score__dot {
  width: 16px; height: 16px;
  border-radius: 50%;
  flex: 0 0 auto;
  box-shadow: inset 0 1px 2px rgba(255, 255, 255, .4), 0 2px 5px rgba(0, 0, 0, .5);
}

.score--black .score__dot { background: radial-gradient(circle at 35% 30%, #444, #050505); }
.score--white .score__dot { background: radial-gradient(circle at 35% 30%, #fff, #cfcfcf); }
.score__label { color: var(--muted); }
.score strong { margin-left: auto; font-size: 20px; }

.turn {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  padding: 9px 16px;
  border-radius: 14px;
  background: linear-gradient(135deg, var(--jade), var(--jade-deep));
  color: #062014;
  font-weight: 800;
  box-shadow: 0 8px 20px rgba(15, 157, 107, .35);
}

.board__frame {
  width: min(100%, 600px);
  aspect-ratio: 1 / 1;
  flex: 0 1 auto;
  padding: clamp(8px, 1.4vw, 14px);
  border-radius: var(--radius-lg);
  background: linear-gradient(150deg, #2a1a0e, #150d07 60%, #221406);
  box-shadow: var(--shadow), inset 0 0 0 1px rgba(255, 215, 130, .08);
}

#gameCanvas {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: 12px;
  cursor: pointer;
  touch-action: manipulation;
  box-shadow: inset 0 0 24px rgba(0, 0, 0, .5);
}

.board__status {
  width: min(100%, 600px);
  margin: 0;
  min-height: 20px;
  padding: 0 4px 2px;
  text-align: center;
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
}

/* ===== 按钮 ===== */
.toolbar {
  width: min(100%, 600px);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
}

.btn {
  min-height: 42px;
  padding: 9px 16px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text);
  font-weight: 700;
  font-size: 15px;
  cursor: pointer;
  transition: transform .16s ease, background .16s ease, box-shadow .16s ease, border-color .16s ease;
}

.btn:hover { transform: translateY(-1px); background: rgba(255, 255, 255, .14); }
.btn:active { transform: translateY(0); }

.btn--primary {
  border-color: transparent;
  background: linear-gradient(135deg, #6ee7b7, var(--jade-deep));
  color: #052014;
  box-shadow: 0 10px 24px rgba(15, 157, 107, .35);
}

.btn--toggle[aria-pressed="false"] { color: var(--muted); background: var(--surface); }
.btn--lg { min-height: 48px; padding: 12px 26px; font-size: 16px; }

/* ===== 侧面板 ===== */
.panel {
  flex: 1 1 330px;
  max-width: 420px;
  min-width: 300px;
  min-height: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
  overflow-y: auto;
  padding-right: 4px;
  scrollbar-width: thin;
  scrollbar-color: rgba(52, 211, 153, .25) transparent;
}

.panel::-webkit-scrollbar {
  width: 5px;
}

.panel::-webkit-scrollbar-track {
  background: transparent;
  border-radius: 99px;
}

.panel::-webkit-scrollbar-thumb {
  background: rgba(52, 211, 153, .22);
  border-radius: 99px;
  transition: background .2s;
}

.panel::-webkit-scrollbar-thumb:hover {
  background: rgba(52, 211, 153, .45);
}

.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
  backdrop-filter: blur(8px);
  padding: 15px;
}

.card h3 {
  margin: 0 0 12px;
  font-size: 16px;
  letter-spacing: .02em;
}

.corner-tip {
  margin: 0;
  min-height: 46px;
  padding: 10px 12px;
  border-radius: 12px;
  background: rgba(251, 191, 36, .1);
  border: 1px solid rgba(251, 191, 36, .28);
  color: var(--gold-soft);
  font-size: 14px;
}

.corner-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin: 12px 0 10px;
}

.corner-cell {
  padding: 9px 10px;
  border-radius: 11px;
  text-align: center;
  font-size: 14px;
  background: var(--surface-2);
  border: 1px solid var(--border-soft);
}

.corner-cell.owned-black { background: #060606; color: #fff; border-color: #000; }
.corner-cell.owned-white { background: #f3f3f0; color: #14201a; border-color: #d4d4cf; }

.corner-summary { margin: 0; color: var(--muted); font-size: 14px; }
.corner-summary strong { color: var(--text); }

.eval-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.eval-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 9px 10px;
  border-radius: 11px;
  background: var(--surface-2);
  border: 1px solid var(--border-soft);
}

.eval-item span { color: var(--muted); font-size: 13px; }
.eval-item strong { font-size: 17px; }
.eval-item--best strong { color: var(--gold); }

.hint-note {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.card--history { flex: 1 1 auto; min-height: 170px; display: flex; flex-direction: column; }

.move-list {
  flex: 1 1 auto;
  min-height: 0;
  margin: 0;
  padding: 0 2px 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  grid-auto-rows: min-content;
  gap: 6px;
  list-style: none;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: rgba(52, 211, 153, .2) transparent;
}

.move-list::-webkit-scrollbar {
  width: 4px;
}

.move-list::-webkit-scrollbar-track {
  background: transparent;
}

.move-list::-webkit-scrollbar-thumb {
  background: rgba(52, 211, 153, .2);
  border-radius: 99px;
}

.move-list::-webkit-scrollbar-thumb:hover {
  background: rgba(52, 211, 153, .4);
}

.move-list button {
  width: 100%;
  min-height: 32px;
  padding: 5px 9px;
  border: 1px solid var(--border-soft);
  border-radius: 9px;
  background: var(--surface-2);
  color: var(--muted);
  text-align: left;
  font-size: 14px;
  cursor: pointer;
  transition: background .15s ease, color .15s ease;
}

.move-list button:hover { background: rgba(255, 255, 255, .14); color: var(--text); }
.move-list .active button { background: var(--gold); color: #1c1405; border-color: var(--gold); font-weight: 700; }

/* ===== 文章/教学内容区 ===== */
.article {
  flex: 0 0 0;
  min-height: 0;
  overflow: hidden;
  margin: 0 20px;
  border-radius: var(--radius);
}

.article.visible {
  flex: 1 1 auto;
  overflow-y: auto;
  padding: 18px;
  border: 1px solid var(--border);
  background: var(--surface);
}

.article__panel { display: none; max-width: 940px; margin: 0 auto; }
.article__panel.active { display: block; }

.article__panel h2 { margin: 0 0 12px; font-size: clamp(19px, 3vw, 26px); }
.article__panel p { color: #d6e6da; }

.teach-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin: 14px 0;
}

.teach-grid div {
  padding: 12px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--border-soft);
}

.teach-grid span { display: block; color: var(--muted); font-size: 13px; }
.teach-grid strong { display: block; margin-top: 4px; color: var(--gold); font-size: 20px; }

.record-summary {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-bottom: 14px;
}

.record-summary span {
  padding: 12px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--border-soft);
  text-align: center;
}

.record-summary strong { display: block; margin-top: 4px; font-size: 22px; color: var(--jade); }

.recent-list { margin: 0; padding-left: 20px; display: grid; gap: 8px; }
.recent-list li { color: #d6e6da; font-size: 14px; }

.guide-list { padding-left: 22px; color: #d6e6da; }
.guide-list li { margin: 6px 0; }

details {
  margin-top: 10px;
  padding: 11px 13px;
  border: 1px solid var(--border);
  border-radius: 13px;
  background: var(--surface);
}

summary { cursor: pointer; color: #fff; font-weight: 700; }
details p { margin: 8px 0 0; }

/* ===== 底部 TabBar（移动端） ===== */
.tabbar {
  flex-shrink: 0;
  order: 999;
  display: flex;
  gap: 4px;
  padding: 8px 10px calc(10px + env(safe-area-inset-bottom));
  background: rgba(4, 10, 7, .96);
  backdrop-filter: blur(16px);
  border-top: 1px solid var(--border-soft);
}

.tab {
  flex: 1 1 0;
  min-width: 0;
  min-height: 52px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  border: 1px solid transparent;
  border-radius: 14px;
  background: transparent;
  color: var(--muted);
  font-weight: 600;
  font-size: 11px;
  letter-spacing: .02em;
  cursor: pointer;
  transition: background .18s, color .18s, border-color .18s;
}

.tab__ico {
  display: block;
  width: 22px;
  height: 22px;
  transition: transform .18s;
}

.tab.active {
  background: rgba(52, 211, 153, .12);
  color: var(--jade);
  border-color: rgba(52, 211, 153, .22);
}

.tab.active .tab__ico { transform: scale(1.12); }

/* ===== 页脚（PC） ===== */
.foot {
  display: none;
  flex: 0 0 auto;
  gap: 14px;
  justify-content: center;
  align-items: center;
  padding: 9px 16px;
  color: var(--muted);
  font-size: 14px;
  background: rgba(0, 0, 0, .3);
  border-top: 1px solid var(--border-soft);
}

/* ===== 结果弹窗 ===== */
.overlay {
  position: fixed;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(3, 8, 6, .72);
  backdrop-filter: blur(6px);
  z-index: 50;
}

.overlay.show { display: flex; }

.overlay__card {
  width: min(100%, 360px);
  padding: 28px 24px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  background: linear-gradient(160deg, #10241a, #0a1610);
  box-shadow: var(--shadow);
  text-align: center;
}

.overlay__icon { margin: 0; font-size: 48px; }
.overlay__title { margin: 8px 0 4px; font-size: 24px; font-weight: 800; }
.overlay__detail { margin: 0 0 18px; color: var(--muted); }

/* ===== PC ===== */
@media (min-width: 900px) {
  html, body { height: auto; }
  body { overflow-y: auto; }
  .app { height: auto; min-height: 100dvh; overflow: visible; }
  .stage {
    flex: 0 0 auto;
    height: calc(100dvh - 90px);
    overflow: hidden;
    justify-content: center;
  }
  .board { flex: 0 1 600px; }
  .tabbar { display: none; }
  .article {
    display: block;
    flex: 0 0 auto;
    min-height: 0;
    overflow: visible;
    padding: 24px;
    margin: 0 auto 20px;
    max-width: 1060px;
    width: calc(100% - 40px);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
  }
  .article__panel { display: block; }
  .article__panel + .article__panel {
    margin-top: 40px;
    padding-top: 40px;
    border-top: 1px solid var(--border-soft);
  }
  .foot { display: flex; }
  .board__frame { width: min(min(100%, 600px), calc(100dvh - 320px)); }
}

/* ===== 移动端 ===== */
@media (max-width: 899px) {
  .topbar { padding-left: 14px; padding-right: 14px; gap: 10px; }
  .ad-slot:not(:empty) { margin: 8px 14px; }

  .stage { flex-direction: column; gap: 12px; padding: 12px 14px 12px; }
  .stage.collapsed { flex: 0 0 0; padding-top: 0; padding-bottom: 0; overflow: hidden; }

  /* 游戏 tab 时隐藏侧面板，让棋盘占满可用空间 */
  .stage:not(.collapsed) .panel { display: none; }

  .board { overflow-y: auto; }
  .board__frame { width: min(100%, calc(100dvh - 330px)); }
  .board__diff-bar { display: flex; }

  .panel {
    max-width: none;
    min-width: 0;
    width: 100%;
    flex: 0 0 auto;
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    overflow: visible;
  }

  .card--history { display: none; }
  .article { margin: 0 14px; }
  .article.visible { margin: 10px 14px 14px; }
}

@media (max-width: 560px) {
  body { font-size: 15px; }
  .topbar__text h1 { font-size: 19px; }
  .scoreboard { gap: 6px; }
  .score { padding: 8px 10px; }
  .score strong { font-size: 18px; }
  .turn { padding: 8px 12px; }
  .panel { grid-template-columns: 1fr; }
  .card--eval { display: none; }
  .board__frame { width: min(100%, calc(100dvh - 330px)); }
  .btn { flex: 1 1 42%; }
}