:root {
  color-scheme: dark light;
  font-family: "Montserrat", "Noto Sans SC", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  /* UI scale controlled by JS fit engine (fallback to 1) */
  --app-scale: 1;
  /* Motion + easing */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  /* 放慢默认时长，使动效更沉稳 */
  --fast: 180ms; --mid: 320ms; --slow: 480ms;
  /* Global background: Light mode — calm paper + cool vignette */
  --bg-gradient:
    radial-gradient(1200px 720px at 15% 18%, rgba(60, 150, 255, 0.10), transparent 60%),
    radial-gradient(1000px 800px at 85% 14%, rgba(80, 220, 180, 0.10), transparent 60%),
    linear-gradient(165deg, #f9fbff, #eef4ff 68%, #eaf2ff);
  /* Panels: frosted-white cards */
  --panel-bg: rgba(255, 255, 255, 0.72);
  --panel-border: rgba(30, 50, 80, 0.12);
  --panel-shadow: 0 12px 34px rgba(107, 133, 166, 0.20);
  --accent: #23b4ff;
  --accent-strong: #0aa0ef;
  /* Text tuned for light UI */
  --text-strong: #17212b;
  --text-dim: rgba(23, 33, 43, 0.62);
  /* Cell size will be tuned by JS; keep a broad clamp for sensible defaults */
  --cell-size: clamp(34px, 8.2vmin, 96px);
  --disc-size: calc(var(--cell-size) * 0.82);
  /* 默认主题：浅色简约（亚麻/浅木调） */
  --board-bg: linear-gradient(135deg, #efe6d6, #e5d2b6);
  --board-border: linear-gradient(145deg, rgba(255, 220, 160, 0.58), rgba(190, 150, 90, 0.42));
  --board-shadow: 0 24px 48px rgba(140, 110, 60, 0.28);
  --hint-color: rgba(30, 140, 240, 0.80);
  --move-ring: rgba(255, 165, 0, 0.95);
  /* Subtle scrollbars (light) */
  --scrollbar-track: rgba(30, 50, 80, 0.06);
  --scrollbar-thumb: rgba(30, 50, 80, 0.28);
  --scrollbar-thumb-hover: rgba(30, 50, 80, 0.42);
  /* Gameover scrim */
  --go-scrim: rgba(10, 14, 20, 0.45);
  /* Selects (light) */
  --select-bg: rgba(255, 255, 255, 0.85);
  --select-border: rgba(30, 50, 80, 0.16);
  --select-fg: #0e1b24;
  --select-arrow: #0e1b24;
}

/* Dark mode palette */
@media (prefers-color-scheme: dark) {
  :root {
    /* Global background: Dark mode — deep slate + neon vignette */
    --bg-gradient:
      radial-gradient(1200px 660px at 16% 18%, rgba(44, 158, 255, 0.16), transparent 60%),
      radial-gradient(1100px 820px at 84% 12%, rgba(120, 70, 255, 0.14), transparent 60%),
      linear-gradient(165deg, #0a1020, #0b1322 64%, #09101a);
    --panel-bg: rgba(16, 20, 28, 0.76);
    --panel-border: rgba(123, 201, 255, 0.16);
    --panel-shadow: 0 12px 42px rgba(0, 0, 0, 0.45);
    --accent: #4dd4ff;
    --accent-strong: #16b8f7;
    --text-strong: #eaf3ff;
    --text-dim: rgba(214, 225, 255, 0.72);
    /* 深色模式下亦保持冷色石板风格（默认主题） */
    --board-bg: linear-gradient(135deg, #0a1b28, #091521);
    --board-border: linear-gradient(145deg, rgba(77, 212, 255, 0.55), rgba(35, 180, 255, 0.38));
    --board-shadow: 0 30px 60px rgba(0, 0, 0, 0.45);
    --hint-color: rgba(77, 212, 255, 0.75);
    --move-ring: rgba(255, 196, 0, 0.95);
    /* Dark scrollbars */
    --scrollbar-track: rgba(255, 255, 255, 0.06);
    --scrollbar-thumb: rgba(200, 220, 255, 0.25);
    --scrollbar-thumb-hover: rgba(200, 220, 255, 0.35);
    --go-scrim: rgba(0, 0, 0, 0.55);
    /* Selects (dark) */
    --select-bg: rgba(16, 20, 28, 0.92);
    --select-border: rgba(123, 201, 255, 0.28);
    --select-fg: #eaf3ff;
    --select-arrow: #a9d8ff;
  }
  /* Component-specific dark tweaks */
  .moves-panel h2, .tips-panel h2 { color: rgba(255, 255, 255, 0.78); }
  .footer { color: rgba(255, 255, 255, 0.6); }
  .footer-info { color: rgba(255, 255, 255, 0.75); }
  button, button.ghost, button.primary { color: #eaf3ff; }
  /* PC 顶部的“外观切换 / 专注对局”按钮在深色模式下加强边框与底 */
  .top-bar #theme,
  .top-bar #focus {
    background: rgba(20, 28, 40, 0.55);
    border-color: rgba(200, 220, 255, 0.42);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.35), inset 0 0 0 1px rgba(200, 220, 255, 0.12);
    backdrop-filter: blur(6px) saturate(1.05);
  }
  .top-bar #theme:hover,
  .top-bar #focus:hover {
    border-color: rgba(77, 212, 255, 0.65);
    background: rgba(28, 38, 52, 0.68);
    box-shadow: 0 10px 26px rgba(0, 0, 0, 0.45), inset 0 0 0 1px rgba(77, 212, 255, 0.16);
  }
  kbd {
    background: rgba(77, 212, 255, 0.18);
    color: #eaf3ff;
    border-color: rgba(77, 212, 255, 0.35);
  }
  .gameover { color: var(--text-strong); }
  .progress .black { background: linear-gradient(90deg, #4a5568, #243040); }
  .progress .white { background: linear-gradient(90deg, #e6e6e6, #bdbdbd); }
  .score { background: rgba(255, 255, 255, 0.04); box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.06); }
  .score.white .label { color: rgba(255, 255, 255, 0.85); }
  .score.black .label { color: rgba(220, 220, 220, 0.8); }
}

/* 强制默认主题的棋盘为浅色（无论系统深浅色），不影响木纹主题 */
.app:not(.theme-wood) {
  --board-bg: linear-gradient(135deg, #efe6d6, #e5d2b6);
  --board-border: linear-gradient(145deg, rgba(255, 220, 160, 0.58), rgba(190, 150, 90, 0.42));
  --board-shadow: 0 24px 48px rgba(140, 110, 60, 0.28);
}

html, body { height: 100%; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg-gradient);
  color: var(--text-strong);
  display: flex;
  align-items: stretch;
  justify-content: center;
  padding: 0;
}

* {
  box-sizing: border-box;
}

a {
  color: inherit;
}

.app {
  min-height: 100vh;
  width: clamp(340px, 98vw, 2100px);
  padding: clamp(18px, 3vw, 32px);
  display: grid;
  grid-template-rows: auto 1fr auto;
  gap: clamp(20px, 3.2vw, 32px);
  transform-origin: top center;
  will-change: transform;
  /* Use CSS variable so JS can scale only when necessary */
  transform: scale(var(--app-scale));
}

/* Fixed viewport wrapper for scale-to-fit */
.fit-root {
  position: fixed;
  inset: 0;
  overflow: hidden;
  display: grid;
  justify-items: center;
  align-content: start;
  /* Pattern layer: ultra-subtle grain so light mode不显单调 */
}

/* Background micro-pattern (light/dark adaptive) */
.fit-root::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  /* dot grid + gentle vignette band */
  background:
    radial-gradient(1200px 40px at 50% -10px, rgba(255,255,255,0.40), rgba(255,255,255,0) 60%),
    radial-gradient(1px 1px at 0 0, rgba(0,0,0,0.06), rgba(0,0,0,0.06) 1px, transparent 1px) 0 0/18px 18px;
  opacity: 0.18;
}
@media (prefers-color-scheme: dark) {
  .fit-root::before {
    background:
      radial-gradient(1200px 40px at 50% -10px, rgba(255,255,255,0.12), rgba(255,255,255,0) 60%),
      radial-gradient(1px 1px at 0 0, rgba(255,255,255,0.15), rgba(255,255,255,0.15) 1px, transparent 1px) 0 0/18px 18px;
    opacity: 0.10;
  }
}
.top-bar { display: grid; gap: 10px; }

.brand {
  display: flex;
  gap: 14px;
  align-items: center;
}

.logo {
  width: clamp(40px, 6vw, 60px);
  height: clamp(40px, 6vw, 60px);
  display: grid;
  place-items: center;
  font-size: clamp(24px, 5vw, 36px);
  border-radius: 18px;
  background: linear-gradient(145deg, #ffd36e, #ff9ed1 60%, #7ad5ff);
  color: var(--text-strong);
  box-shadow: 0 10px 22px rgba(255, 174, 74, 0.35);
}

.title-wrap h1 {
  margin: 0;
  font-size: clamp(18px, 3.4vw, 28px);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: linear-gradient(90deg, #0f6ab9, #039d7a, #ff8a3d);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.title-wrap p {
  margin: 4px 0 0;
  font-size: clamp(10px, 2vw, 13px);
  color: var(--text-dim);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.status-panels { display: grid; gap: 12px; grid-template-columns: 1fr; }

.panel {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 18px;
  padding: clamp(12px, 2vw, 18px);
  box-shadow: var(--panel-shadow);
  backdrop-filter: blur(14px) saturate(1.1);
  min-width: 240px;
  animation: panelIn var(--slow) var(--ease) both;
}
.status-panels .panel:nth-child(1) { animation-delay: 30ms; }
.status-panels .panel:nth-child(2) { animation-delay: 90ms; }
.status-panels .panel:nth-child(3) { animation-delay: 150ms; }

.score-panel { display: grid; grid-template-rows: auto auto auto; gap: 8px; }

.scores {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 18px;
}

.score {
  text-align: center;
  flex: 1;
  background: rgba(20, 40, 60, 0.05);
  border-radius: 12px;
  padding: 12px;
  box-shadow: inset 0 0 0 1px rgba(20, 40, 60, 0.08);
}

.score .label {
  display: block;
  font-size: 0.85rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.score.white .label, .score.black .label { color: var(--text-dim); }

.score .value {
  display: block;
  font-size: clamp(20px, 2.6vw, 30px);
  font-weight: 800;
  margin-top: 6px;
  letter-spacing: 0.1em;
}

.progress {
  display: flex;
  height: 8px;
  border-radius: 6px;
  overflow: hidden;
  background: linear-gradient(90deg, rgba(230, 236, 245, 0.9), rgba(240, 250, 255, 0.6));
  border: 1px solid rgba(20, 40, 60, 0.08);
}

.progress span { flex-basis: 50%; transition: flex-basis 200ms ease; }
.progress .black { background: linear-gradient(90deg, #566173, #2d3c4e); }
.progress .white { background: linear-gradient(90deg, #f0f0f0, #cfcfcf); }

/* 分数条变更时的脉冲高亮动画 */
.progress.pulse .black,
.progress.pulse .white {
  animation: barPulse 420ms ease-out both;
}
@keyframes barPulse {
  0% { filter: brightness(1.05); box-shadow: inset 0 0 0 0 rgba(35, 180, 255, 0.16); }
  60% { filter: brightness(1.0); box-shadow: inset 0 0 0 6px rgba(35, 180, 255, 0.08); }
  100% { filter: none; box-shadow: none; }
}

.turn { font-size: 1rem; font-weight: 600; color: var(--text-strong); }

.msg { min-height: 1.2em; color: var(--text-dim); font-size: 0.95rem; }

.cpu-panel { min-width: 0; }

.cpu-panel h2 {
  margin: 0 0 12px;
  font-size: 1rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.control-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 12px;
}

label { font-size: 0.85rem; color: var(--text-dim); display: flex; flex-direction: column; gap: 6px; }

/* 隐藏原生 select，保留在 DOM 用于逻辑与回退 */
select.enhanced-native {
  position: absolute !important;
  width: 1px !important; height: 1px !important;
  padding: 0 !important; margin: -1px !important;
  overflow: hidden !important; clip: rect(0,0,0,0) !important;
  white-space: nowrap !important; border: 0 !important;
}

/* 自定义下拉：按钮 + 漂浮面板 */
.fancy-select { position: relative; width: 100%; }
.fancy-select .fs-btn {
  display: flex; align-items: center; justify-content: flex-start;
  gap: 8px; width: 100%;
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--select-bg);
  color: var(--select-fg);
  border: 1px solid var(--select-border);
  font-size: 0.95rem; font-weight: 600;
  cursor: pointer;
  transition: border 160ms ease, box-shadow 160ms ease, background 160ms ease, transform 160ms ease;
}
.fancy-select .fs-btn:hover { border-color: rgba(35, 180, 255, 0.35); transform: translateY(-1px); }
.fancy-select .fs-btn:focus { outline: none; box-shadow: 0 0 0 3px rgba(35, 180, 255, 0.25); border-color: var(--accent); }
.fancy-select .fs-btn::after {
  content: ""; display: block; width: 10px; height: 6px; margin-left: auto;
  background: var(--select-arrow);
  clip-path: polygon(50% 100%, 0 0, 100% 0);
  opacity: 0.75; transition: transform 160ms ease, opacity 160ms ease;
}
.fancy-select.open .fs-btn::after { transform: rotate(180deg); opacity: 0.9; }
.fancy-select .fs-panel {
  position: absolute; left: 0; right: 0; top: calc(100% + 8px);
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 12px; box-shadow: var(--panel-shadow);
  backdrop-filter: blur(14px) saturate(1.1);
  padding: 6px; display: none; z-index: 50;
  max-height: min(320px, 40vh); overflow: auto;
  animation: fsPanelIn var(--mid) var(--ease) both;
}
.fancy-select.open .fs-panel { display: block; }
@keyframes fsPanelIn { from { transform: translateY(6px); opacity: 0; } to { transform: none; opacity: 1; } }
.fs-option { display: flex; align-items: center; gap: 8px; padding: 10px 10px; border-radius: 8px; cursor: pointer; color: var(--text-strong); }
.fs-option:hover { background: rgba(35, 180, 255, 0.12); }
.fs-option[aria-selected="true"] { background: rgba(35, 180, 255, 0.18); font-weight: 700; }
.fs-option .fs-badge { margin-left: auto; font-size: 0.72rem; color: var(--text-dim); opacity: 0.85; }

/* Label 内布局：让自定义下拉撑满 */
label .fancy-select { margin-top: 6px; }

.switch {
  position: relative;
  padding-left: 52px;
  align-items: center;
  min-height: 32px;
}

.switch input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}

.switch .slider {
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 44px;
  height: 24px;
  background: rgba(140, 160, 190, 0.35);
  border-radius: 12px;
  transition: background 160ms ease;
}

.switch .slider::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 3px;
  width: 18px;
  height: 18px;
  background: rgba(255, 255, 255, 0.95);
  border-radius: 50%;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.switch input:checked + .slider { background: rgba(35, 180, 255, 0.6); }

.switch input:checked + .slider::before {
  transform: translateX(20px);
  box-shadow: 0 0 12px rgba(35, 180, 255, 0.55);
}

.actions {
  margin-top: 18px;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

button {
  padding: 10px 18px;
  border-radius: 10px;
  border: 1px solid transparent;
  background: linear-gradient(145deg, rgba(35, 180, 255, 0.18), rgba(255, 180, 80, 0.18));
  color: var(--text-strong);
  font-size: 0.95rem;
  letter-spacing: 0.04em;
  font-weight: 600;
  cursor: pointer;
  transition: transform var(--fast) var(--ease-out), box-shadow var(--mid) var(--ease-out), border var(--mid) var(--ease-out), background var(--mid) var(--ease-out);
  position: relative;
  overflow: hidden;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 24px rgba(35, 180, 255, 0.25);
  border-color: rgba(35, 180, 255, 0.35);
}

button:active { transform: translateY(0) scale(0.98); }

/* 移除点击涟漪，保留干净的点击态（更稳重） */
/* 可选：若未来需要再启用，建议仅在重要按钮上局部添加 */

button.primary { background: linear-gradient(145deg, #23b4ff, #ffa74d); color: var(--text-strong); }

button.ghost { background: transparent; border-color: rgba(30, 50, 80, 0.22); color: var(--text-strong); }

button.sm { padding: 6px 10px; font-size: 0.85rem; }

/* 浅色模式下：顶部“外观切换/专注对局”按钮更清晰的边界与底色 */
@media (prefers-color-scheme: light) {
  .top-bar #theme,
  .top-bar #focus {
    background: rgba(255, 255, 255, 0.72);
    border-color: rgba(30, 50, 80, 0.28);
    box-shadow: 0 6px 18px rgba(107, 133, 166, 0.18), inset 0 0 0 1px rgba(255, 255, 255, 0.45);
    backdrop-filter: blur(6px) saturate(1.05);
  }
  .top-bar #theme:hover,
  .top-bar #focus:hover {
    border-color: rgba(35, 180, 255, 0.55);
    background: rgba(255, 255, 255, 0.86);
    box-shadow: 0 10px 26px rgba(107, 133, 166, 0.28), inset 0 0 0 1px rgba(35, 180, 255, 0.16);
  }
}

.arena { display: grid; grid-template-columns: 1fr clamp(260px, 28vw, 420px); gap: clamp(16px, 2.6vw, 26px); align-items: start; min-height: 0; }

.board-wrap {
  position: relative;
  justify-self: center;
}

#board {
  display: grid;
  grid-template-columns: repeat(8, var(--cell-size));
  grid-template-rows: repeat(8, var(--cell-size));
  gap: calc(var(--cell-size) * 0.045);
  background: var(--board-bg);
  padding: calc(var(--cell-size) * 0.1);
  border: 12px solid transparent;
  border-radius: clamp(16px, 3vw, 26px);
  box-shadow: var(--board-shadow);
  position: relative;
  overflow: hidden;
  animation: boardIn var(--slow) var(--ease) both;
}

/* 移动端顶部计分板：默认隐藏，小屏显示 */
.mobile-score { display: none; }

/* 设置抽屉的遮罩层 */
.overlay-scrim {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
  z-index: 1000;
}
.overlay-scrim[hidden] { display: none; }

#board::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 3px;
  background: var(--board-border);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}

/* 默认主题的棋盘纹理（轻纸纹 + 顶部高光） */
#board::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  /* 叠加细腻纸纹与高光（无铆钉） */
  background:
    repeating-linear-gradient(90deg, rgba(255,255,255,0.06) 0, rgba(255,255,255,0.06) 2px, rgba(0,0,0,0.05) 3px, rgba(0,0,0,0.05) 5px),
    radial-gradient(1200px 700px at 50% -10%, rgba(255,255,255,0.22), rgba(255,255,255,0) 60%);
  mix-blend-mode: soft-light;
  pointer-events: none;
}

.cell {
  width: var(--cell-size);
  height: var(--cell-size);
  /* 默认主题：浅色亚麻/浅木格（对黑白子皆有对比） */
  background:
    radial-gradient(18px 18px at 30% 28%, rgba(255,255,255,0.25), rgba(255,255,255,0) 70%),
    linear-gradient(180deg, #f7f1e6, #e9dcc7),
    repeating-linear-gradient(120deg, rgba(0,0,0,0.03) 0px, rgba(0,0,0,0.03) 3px, rgba(255,255,255,0.06) 4px, rgba(255,255,255,0.06) 7px);
  background-blend-mode: screen, multiply, normal;
  border-radius: clamp(8px, 1.4vw, 12px);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: inset 0 -3px 6px rgba(0, 0, 0, 0.35);
  cursor: pointer;
  transition: transform var(--mid) var(--ease-out), box-shadow var(--mid) var(--ease-out), outline-color var(--mid) var(--ease-out);
  contain: layout paint;
}

.cell:hover {
  outline: 2px solid rgba(255, 174, 74, 0.30);
  transform: translateY(-1px) scale(1.012);
  box-shadow: inset 0 -3px 6px rgba(0, 0, 0, 0.35), 0 6px 18px rgba(0,0,0,0.2);
}

.disc {
  width: var(--disc-size);
  height: var(--disc-size);
  border-radius: 50%;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.45);
  transform-origin: center;
  position: relative;
  will-change: transform, filter; /* smoother animation on file:// */
}

/* 棋子渐变（更立体，带边缘高光与柔和高亮） */
.disc.black {
  background:
    radial-gradient(65% 60% at 30% 28%, #6a6a6a, #141414 70%),
    radial-gradient(38% 36% at 70% 78%, rgba(255,255,255,0.14), rgba(255,255,255,0) 70%),
    conic-gradient(from 220deg at 50% 50%, rgba(255,255,255,0.08), rgba(255,255,255,0) 40%);
}
.disc.white {
  background:
    radial-gradient(65% 60% at 30% 28%, #ffffff, #d8d8d8 72%),
    radial-gradient(38% 36% at 70% 78%, rgba(255,255,255,0.65), rgba(255,255,255,0) 70%),
    conic-gradient(from 220deg at 50% 50%, rgba(255,255,255,0.18), rgba(255,255,255,0) 40%);
}
/* 细窄外圈，暗示厚度 */
.disc::before {
  content: "";
  position: absolute; inset: 0;
  border-radius: 50%;
  box-shadow: inset 0 0 0 1.5px rgba(0,0,0,0.28), inset 0 6px 8px rgba(0,0,0,0.18);
  pointer-events: none;
}

/* 新：使用 .hint-dot 元素避免与坐标伪元素冲突 */
.hint::after { content: none; }
.hint-dot {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 12px;
  height: 12px;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: var(--hint-color);
  opacity: 0.66;
  box-shadow: 0 0 8px rgba(77,212,255,0.45);
  animation: hintPulse 1.4s var(--ease-out) infinite;
  pointer-events: none;
}

@keyframes hintPulse {
  0% { transform: translate(-50%, -50%) scale(0.85); opacity: 0.5; }
  50% { transform: translate(-50%, -50%) scale(1); opacity: 0.95; }
  100% { transform: translate(-50%, -50%) scale(0.85); opacity: 0.5; }
}

.last-move::after { content: none; }
.cell.last-move .disc::after {
  content: "";
  position: absolute;
  inset: 0; /* 跟随棋子本体尺寸，避免比例误差 */
  border-radius: 50%;
  box-sizing: border-box;
  /* 使用外发光描边形成环，更稳定不变形 */
  box-shadow:
    0 0 0 3px var(--move-ring),
    0 0 16px rgba(255, 196, 0, 0.55),
    inset 0 0 10px rgba(255, 196, 0, 0.35);
  pointer-events: none;
  animation: ringPop 420ms var(--ease-out) both;
}

/* no pulsing to reduce distraction */

.disc.place { animation: placeDrop 560ms var(--ease-out) both; }
@keyframes placeDrop {
  0%   { transform: translateY(-16%) scale(0.94) rotateX(3deg); filter: brightness(1.02); }
  55%  { transform: translateY(0)    scale(1.015) rotateX(0deg); filter: brightness(1.0); }
  80%  { transform: translateY(-1%)  scale(0.997); }
  100% { transform: translateY(0)    scale(1); }
}

/* playful sparkle burst when placing */
.disc.place::before {
  content: "";
  position: absolute;
  inset: -6px;
  border-radius: 50%;
  background: radial-gradient(circle at center, rgba(255, 210, 90, 0.5), rgba(255, 210, 90, 0) 60%);
  animation: burst 520ms ease-out both;
  pointer-events: none;
}
@keyframes burst {
  0% { transform: scale(0.75); opacity: 0.85; }
  100% { transform: scale(1.18); opacity: 0; }
}

/* 翻子：颜色渐变切换（旧色覆盖层淡出，露出新色） */
.disc.colorflip { /* 保持静态，无 3D 翻转 */ }
.disc.colorflip::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 50%;
  pointer-events: none;
  opacity: 1;
  /* 延迟沿用 --flip-delay，形成连锁波次 */
  /* 稍微放慢渐变节奏（原 480ms -> 560ms） */
  animation: colorFade 560ms var(--ease) both;
  animation-delay: var(--flip-delay, 0ms);
}
/* 新子为黑：覆盖层展示旧的白色外观，淡出以显露黑色底 */
.disc.black.colorflip::after {
  background:
    radial-gradient(65% 60% at 30% 28%, #ffffff, #d8d8d8 72%),
    radial-gradient(38% 36% at 70% 78%, rgba(255,255,255,0.65), rgba(255,255,255,0) 70%),
    conic-gradient(from 220deg at 50% 50%, rgba(255,255,255,0.18), rgba(255,255,255,0) 40%);
}
/* 新子为白：覆盖层展示旧的黑色外观，淡出以显露白色底 */
.disc.white.colorflip::after {
  background:
    radial-gradient(65% 60% at 30% 28%, #6a6a6a, #141414 70%),
    radial-gradient(38% 36% at 70% 78%, rgba(255,255,255,0.14), rgba(255,255,255,0) 70%),
    conic-gradient(from 220deg at 50% 50%, rgba(255,255,255,0.08), rgba(255,255,255,0) 40%);
}
@keyframes colorFade {
  from { opacity: 1; }
  to   { opacity: 0; }
}

/* 坐标显示（首列显示行号，底行显示列字母） */
#board.show-coords .cell[data-col="0"]::before {
  content: attr(data-rowlabel);
  position: absolute;
  left: calc(-0.6rem - 6px);
  color: rgba(255,255,255,0.7);
  font-size: 0.8rem;
  line-height: 1;
}

#board.show-coords .cell[data-row="7"]::after {
  content: attr(data-collabel);
  position: absolute;
  bottom: calc(-0.8rem - 6px);
  color: rgba(255,255,255,0.7);
  font-size: 0.8rem;
  line-height: 1;
}

.board-shadow {
  position: absolute;
  inset: -20px;
  background: radial-gradient(70% 80% at 50% 110%, rgba(60, 80, 100, 0.18), transparent 70%);
  filter: blur(16px);
  z-index: -1;
}

/* 对局结束覆盖层 */
.gameover[hidden] { display: none; }
.gameover {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--go-scrim);
  color: var(--text-strong);
  transition: background var(--mid) var(--ease);
}
.gameover::before { content: none; display: none; }
.go-card {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 16px;
  padding: clamp(14px, 2.6vw, 20px);
  box-shadow: var(--panel-shadow);
  min-width: clamp(220px, 36vw, 420px);
  text-align: center;
  backdrop-filter: blur(8px) saturate(1.05);
  transform-origin: center;
  position: relative;
  z-index: 3;
  animation: goPop var(--mid) var(--ease-out);
  transition: transform var(--mid) var(--ease);
}
.gameover .go-title { font-size: clamp(18px, 2.6vw, 24px); font-weight: 800; margin-bottom: 6px; }
.gameover .go-sub { color: var(--text-dim); margin-bottom: 12px; }
.go-actions { display: flex; gap: 10px; justify-content: center; }

@keyframes goPop {
  from { transform: scale(0.92); opacity: 0; }
  to   { transform: scale(1);    opacity: 1; }
}

/* 回顾棋局：将覆盖层缩小到右上角，背景透明，允许查看棋盘 */
.gameover.docked { background: transparent; place-items: start center; padding: 0; pointer-events: none; }
.gameover.docked .go-card {
  position: absolute;
  top: 0; left: 50%;
  /* collapse to just above board (small gap) */
  transform: translate(-50%, calc(-100% - 6px)) scale(0.90);
  min-width: clamp(220px, 36vw, 420px);
  pointer-events: auto;
  transition: transform var(--mid) var(--ease);
}
/* 热区或显式 reveal 时，展开胜利卡；悬停卡片自身保持展开 */
.go-hotspot:hover + .gameover.docked .go-card,
.gameover.docked.reveal .go-card,
.gameover.docked .go-card:hover {
  transform: translate(-50%, 0) scale(1);
}

/* 顶部热区：负责 hover 捕获（默认始终存在；未 dock 时被覆盖层拦截） */
.go-hotspot { position: absolute; left: 50%; top: 0; transform: translate(-50%, -100%); width: clamp(220px, 36vw, 420px); height: 20px; z-index: 2; pointer-events: auto; }
.go-hotspot::after { content: ''; position: absolute; inset: 0; border-radius: 14px; opacity: 0; transition: opacity 160ms ease; }
.go-hotspot:hover::after { opacity: 0.18; }


/* 小提示：悬停棋盘即可展开（自动淡出） */
.go-hint {
  position: absolute;
  top: 0; left: 50%;
  transform: translate(-50%, -120%);
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 999px;
  padding: 6px 10px;
  font-size: 12px; color: var(--text-strong);
  box-shadow: var(--panel-shadow);
  backdrop-filter: blur(8px) saturate(1.05);
  opacity: 0;
  animation: hintInOut 2000ms var(--ease) forwards;
  pointer-events: none;
}
@keyframes hintInOut {
  0%   { opacity: 0; transform: translate(-50%, -130%); }
  12%  { opacity: 1; transform: translate(-50%, -120%); }
  75%  { opacity: 1; transform: translate(-50%, -120%); }
  100% { opacity: 0; transform: translate(-50%, -130%); }
}

/* 胜利/失败特效容器（覆盖层内） */
.go-effects { position: absolute; inset: 0; pointer-events: none; overflow: hidden; z-index: 0; }

/* 胜利：五彩纸屑轻盈下落 */
.gameover.win .go-effects { opacity: 1; }
.gameover.win .go-effects .confetti { position: absolute; inset: 0; }
.gameover.win .go-effects .confetti span {
  position: absolute;
  top: -10%;
  left: var(--x, 50%);
  width: var(--size, 8px);
  height: var(--size, 14px);
  background: hsl(var(--h, 200) 90% 60%);
  transform: rotate(var(--rot, 0deg));
  opacity: 0.95;
  border-radius: 2px;
  animation: confettiFall var(--dur, 1400ms) linear var(--delay, 0ms) forwards;
}
@keyframes confettiFall {
  0%   { transform: translateY(0) rotate(0deg); }
  100% { transform: translateY(120vh) rotate(360deg); }
}

/* 失败：轻微震动 + 暗角压抑氛围 */
.gameover.lose .go-card { animation: loseShake 600ms var(--ease); }
.gameover.lose::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(140% 120% at 50% 10%, rgba(255,0,60,0.10), transparent 60%),
              radial-gradient(70% 90% at 50% 120%, rgba(0,0,0,0.28), transparent 60%);
  pointer-events: none;
}
@keyframes loseShake {
  0% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(5px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(3px); }
  100% { transform: translateX(0); }
}

.sidebar { display: grid; gap: 12px; max-height: 100%; overflow: auto; }

.moves-panel, .tips-panel {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 16px;
  padding: 16px;
  box-shadow: var(--panel-shadow);
}

.moves-panel h2, .tips-panel h2 {
  margin: 0 0 12px;
  font-size: 0.95rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-dim);
}

#move-list {
  margin: 0;
  padding-left: 1.4em;
  font-variant-numeric: tabular-nums;
  /* Keep the whole UI within one page: shorter panel to free room for board */
  max-height: clamp(100px, 22vh, 220px);
  overflow: auto;
}

#move-list li { margin: 4px 0; opacity: 0.86; animation: fadeSlide 240ms var(--ease-out) both; }
#move-list li:last-child { color: var(--accent-strong); font-weight: 700; }

.tips-panel ul {
  margin: 0;
  padding-left: 1.2em;
  list-style: none;
  display: grid;
  gap: 8px;
}

.tips-panel li { color: var(--text-dim); display: flex; align-items: center; gap: 10px; }

kbd {
  font-family: inherit;
  background: rgba(35, 180, 255, 0.18);
  color: var(--text-strong);
  border-radius: 8px;
  padding: 4px 8px;
  border: 1px solid rgba(35, 180, 255, 0.35);
  font-size: 0.9rem;
}

.footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-dim);
  font-size: 0.85rem;
}

.footer-info { color: var(--text-dim); }

/* Thinking spinner */
#msg.thinking::before, #turn.thinking::before {
  content: "";
  display: inline-block;
  width: 0.9em;
  height: 0.9em;
  margin-right: 6px;
  border-radius: 50%;
  border: 2px solid rgba(35, 180, 255, 0.7);
  border-top-color: transparent;
  animation: spin 0.8s linear infinite;
  vertical-align: -0.1em;
}

@keyframes spin {
  from { transform: rotate(0); }
  to { transform: rotate(360deg); }
}

/* --- UI Animations --- */
@keyframes panelIn { from { transform: translateY(6px); opacity: 0; } to { transform: none; opacity: 1; } }
@keyframes boardIn { from { transform: translateY(8px) scale(0.995); opacity: 0; } to { transform: none; opacity: 1; } }
@keyframes discIn { from { transform: scale(0.98); opacity: 0.0; } to { transform: scale(1); opacity: 1; } }
@keyframes ringPop { from { box-shadow: 0 0 0 0 rgba(255,196,0,0.0), 0 0 0 rgba(0,0,0,0); } to { box-shadow: 0 0 0 3px var(--move-ring), 0 0 16px rgba(255, 196, 0, 0.55), inset 0 0 10px rgba(255, 196, 0, 0.35); } }
@keyframes fadeSlide { from { transform: translateY(6px); opacity: 0; } to { transform: none; opacity: 1; } }
/* ripple 已移除 */

/* Responsive */
/* 默认隐藏移动端设置抽屉的标题栏，仅在小屏显示 */
.mobile-settings-header { display: none; }
@media (max-width: 1080px) {
  .top-bar {
    grid-template-columns: 1fr;
  }
  .arena {
    grid-template-columns: 1fr;
    justify-items: center; /* ensure all children center on small screens */
  }
  /* 进一步确保棋盘容器在移动端水平居中 */
  .board-wrap { justify-self: center; margin-inline: auto; }
  /* 棋盘细节微调：缩小边距与网格缝隙，增大有效棋面 */
  #board { gap: calc(var(--cell-size) * 0.035); padding: calc(var(--cell-size) * 0.08); border-radius: clamp(14px, 3vw, 22px); }
  /* 移动端：默认隐藏侧栏，避免占据棋盘下方空间 */
  .sidebar { display: none; }
  /* 顶部计分板显示，侧栏中的计分板隐藏（避免重复） */
  /* 使用容器相对宽度，避免 96vw 超出 .app 内容区导致看起来“偏右” */
  .mobile-score {
    display: block;
    width: 100%;
    max-width: 640px;
    margin-inline: auto;
    justify-self: center;
  }
  .sidebar .score-panel { display: none; }
  /* 显示“设置”按钮，隐藏专注按钮 */
  #settings { display: inline-flex !important; }
  #focus { display: none !important; }
}

@media (max-width: 720px) {
  .brand { justify-content: center; }
  .footer { flex-direction: column; gap: 8px; text-align: center; }
}

/* When scaled down a lot, tighten paddings slightly */
@media (max-height: 640px) {
  .panel { padding: 14px; }
  .actions { margin-top: 12px; }
}

/* 专注对局模式：隐藏侧栏，棋盘最大化 */
.app.focus-mode .sidebar { display: none !important; }
.app.focus-mode .arena { grid-template-columns: 1fr; }

/* 移动端设置抽屉样式（在 .settings-open 时显示） */
@media (max-width: 1080px) {
  .app.settings-open .overlay-scrim { display: block; }
  .app.settings-open .sidebar {
    display: block;
    position: fixed;
    left: 0; right: 0; bottom: 0;
    top: auto;
    width: 100vw;
    max-height: min(82vh, 640px);
    overflow: auto;
    padding: 14px 16px 18px;
    border-top-left-radius: 18px;
    border-top-right-radius: 18px;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    box-shadow: 0 -10px 34px rgba(0, 0, 0, 0.35);
    backdrop-filter: blur(14px) saturate(1.1);
    z-index: 1100;
    animation: drawerIn var(--mid) var(--ease) both;
  }
  @keyframes drawerIn { from { transform: translateY(12px); opacity: 0; } to { transform: none; opacity: 1; } }
  /* 移动端设置抽屉标题栏 */
  .mobile-settings-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    margin: 4px 0 10px;
  }
  .mobile-settings-header .msh-title {
    font-size: 0.92rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--text-dim);
  }
}

/* ================================== */
/* 主题：木纹棋盘 + 绿色绒面格子       */
/* ================================== */
.app.theme-wood {
  /* 更克制的温暖底色（纸质感） */
  --bg-gradient:
    radial-gradient(1000px 700px at 12% 12%, rgba(230, 180, 120, 0.06), transparent 60%),
    radial-gradient(900px 900px at 86% 14%, rgba(210, 150, 110, 0.05), transparent 60%),
    linear-gradient(160deg, #f9f4ec, #fffaf2);
  /* 木框主体：浅色栎/枫木 + 油蜡光晕分层 */
  --board-bg:
    linear-gradient(94deg, #e6c79c 0%, #d6b383 32%, #cda574 62%, #e2c492 100%),
    radial-gradient(140% 110% at 50% -10%, rgba(255, 238, 200, 0.46), rgba(255, 238, 200, 0)),
    linear-gradient(180deg, rgba(255, 245, 220, 0.24), rgba(255, 245, 220, 0) 28%, rgba(0,0,0,0.18) 90%, rgba(0,0,0,0.22));
  /* 倒角高光（上左）与阴影（下右） */
  --board-border: linear-gradient(145deg, rgba(255, 232, 180, 0.60), rgba(160, 110, 60, 0.35));
  --board-shadow: 0 22px 48px rgba(120, 90, 40, 0.28);
  /* 提示光圈统一为清亮蓝 */
  --hint-color: rgba(30, 140, 240, 0.80);
}
.app.theme-wood #board {
  background: var(--board-bg);
}
.app.theme-wood #board::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
  /* 新木纹：多频率纵向纹理 + 微妙结疤 + 漆面高光 */
  background:
    /* 主纤维：柔波状深浅交替 */
    repeating-linear-gradient(97deg,
      rgba(255, 232, 200, 0.045) 0px,
      rgba(255, 232, 200, 0.045) 5px,
      rgba(62, 34, 16, 0.07) 6px,
      rgba(62, 34, 16, 0.07) 14px
    ),
    /* 次级纤维：短节理，避免完美平行 */
    repeating-linear-gradient(86deg,
      rgba(255, 242, 214, 0.028) 0px,
      rgba(255, 242, 214, 0.028) 2px,
      rgba(38, 22, 10, 0.05) 3px,
      rgba(38, 22, 10, 0.05) 6px
    ),
    /* 结疤/猫眼：两处柔和高光+暗影 */
    radial-gradient(360px 240px at 26% 32%, rgba(255, 214, 158, 0.20), rgba(90, 50, 24, 0.0) 70%),
    radial-gradient(420px 300px at 74% 68%, rgba(255, 210, 150, 0.18), rgba(80, 44, 20, 0.0) 68%),
    /* 边缘加深 + 光亮（覆盖整板） */
    radial-gradient(120% 140% at 50% 120%, rgba(0, 0, 0, 0.22), transparent 70%),
    linear-gradient(180deg, rgba(255,255,255,0.18), transparent 26%, rgba(0,0,0,0.22) 86%, rgba(0,0,0,0.28));
  mix-blend-mode: soft-light;
  opacity: 0.96;
}
.app.theme-wood .cell {
  /* 浅木格：枫/桦木调，细纤维 + 微高光（无绿色） */
  background:
    radial-gradient(18px 18px at 30% 28%, rgba(255,255,255,0.22), rgba(255,255,255,0) 70%),
    linear-gradient(180deg, #f6e7cd, #e9cfa9),
    repeating-linear-gradient(95deg,
      rgba(255, 238, 210, 0.24) 0px,
      rgba(255, 238, 210, 0.24) 3px,
      rgba(160, 120, 80, 0.08) 4px,
      rgba(160, 120, 80, 0.08) 8px
    );
  background-blend-mode: screen, multiply, normal;
  box-shadow: inset 0 -3px 6px rgba(0,0,0,0.22), inset 0 10px 22px rgba(255,255,255,0.08);
}
.app.theme-wood .cell:hover { outline: 2px solid rgba(230, 160, 60, 0.28); }
.app.theme-wood .board-shadow {
  background: radial-gradient(72% 82% at 50% 110%, rgba(120, 90, 40, 0.20), transparent 72%);
}


/* ------------------------------- */
/* Decorative playful floating dots */
/* ------------------------------- */
/* Legacy bubbles kept but hidden to avoid style clash */
.decor-bubbles { display: none; }

/* ================================ */
/* Othello-themed ambient ornaments */
/* ================================ */
.decor-othello {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0; /* sit behind .app */
}
.decor-othello canvas.bgfx {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  filter: saturate(1.02);
}
.decor-othello .orb {
  position: absolute;
  left: var(--x, 50%);
  top: var(--y, 50%);
  width: calc(var(--s, 120) * 1px);
  height: calc(var(--s, 120) * 1px);
  transform: translate(-50%, -50%) rotate(var(--rot, 0deg));
  border-radius: 999px;
  opacity: 0.22; /* gentle by default */
  filter: drop-shadow(0 12px 28px rgba(0, 0, 0, 0.18));
  animation: drift 26s ease-in-out calc(var(--delay, 0) * 1s) infinite alternate;
}
.decor-othello .orb.ring {
  background:
    radial-gradient(closest-side, transparent calc(50% - 6px), rgba(255,255,255,0.9) calc(50% - 5.8px) 50%, transparent 52%),
    radial-gradient(closest-side, rgba(255,255,255,0.25), rgba(255,255,255,0) 60%);
  mix-blend-mode: overlay;
}
.decor-othello .orb.solid {
  background:
    radial-gradient(62% 62% at 30% 30%, rgba(255,255,255,0.8), rgba(255,255,255,0.0) 70%),
    radial-gradient(closest-side, rgba(255,255,255,0.24), rgba(0,0,0,0.10));
}
.decor-othello .orb.split {
  background:
    conic-gradient(from 90deg, rgba(255,255,255,0.96) 0 180deg, rgba(0,0,0,0.92) 180deg 360deg),
    radial-gradient(60% 60% at 35% 35%, rgba(255,255,255,0.8), rgba(255,255,255,0) 70%);
  box-shadow: inset 0 0 0 1.5px rgba(0,0,0,0.25);
}
/* Rail: soft moving band along edges */
.decor-othello .rail {
  position: absolute;
  width: var(--w, 46vw);
  height: var(--h, 30vh);
  left: var(--x, 0);
  top: var(--y, 0);
  transform: rotate(var(--rot, 0deg));
  filter: blur(18px) saturate(1.05);
  opacity: 0.20;
  animation: pan 36s linear calc(var(--delay, 0) * 1s) infinite;
  background:
    linear-gradient(90deg,
      rgba(255,255,255,0) 0%,
      rgba(255,255,255,0.65) 16%,
      rgba(255,255,255,0.0) 32%,
      rgba(255,255,255,0.0) 100%);
}
/* Arc: ring segment glow */
.decor-othello .arc {
  position: absolute;
  width: calc(var(--s, 440) * 1px);
  height: calc(var(--s, 440) * 1px);
  left: var(--x, 50%);
  top: var(--y, 50%);
  transform: translate(-50%, -50%) rotate(var(--rot, 0deg));
  border-radius: 999px;
  opacity: 0.22;
  background: radial-gradient(closest-side, transparent calc(50% - 2px), rgba(255,255,255,0.9) calc(50% - 2px) calc(50% + 2px), transparent calc(50% + 2px));
  /* show only a segment */
  -webkit-mask: conic-gradient(from var(--a, 0deg), transparent, #000 8deg 120deg, transparent 130deg);
  mask: conic-gradient(from var(--a, 0deg), transparent, #000 8deg 120deg, transparent 130deg);
  filter: drop-shadow(0 12px 28px rgba(0,0,0,0.16));
  animation: spin 60s linear infinite;
}
@media (prefers-color-scheme: dark) {
  .decor-othello .orb { opacity: 0.26; }
  .decor-othello .orb.ring {
    background:
      radial-gradient(closest-side, transparent calc(50% - 6px), rgba(140,210,255,0.95) calc(50% - 5.8px) 50%, transparent 52%),
      radial-gradient(closest-side, rgba(77,212,255,0.25), rgba(77,212,255,0) 60%);
  }
  .decor-othello .orb.solid {
    background:
      radial-gradient(62% 62% at 30% 30%, rgba(180,220,255,0.68), rgba(180,220,255,0.0) 70%),
      radial-gradient(closest-side, rgba(130,190,255,0.24), rgba(0,0,0,0.30));
  }
  .decor-othello .orb.split {
    background:
      conic-gradient(from 90deg, rgba(230,240,255,0.95) 0 180deg, rgba(0,0,0,0.92) 180deg 360deg),
      radial-gradient(60% 60% at 35% 35%, rgba(200,230,255,0.55), rgba(200,230,255,0) 70%);
    box-shadow: inset 0 0 0 1.5px rgba(120, 180, 255, 0.25);
  }
  .decor-othello .rail {
    opacity: 0.18;
    background:
      linear-gradient(90deg,
        rgba(77,212,255,0) 0%,
        rgba(77,212,255,0.65) 16%,
        rgba(77,212,255,0.0) 32%,
        rgba(77,212,255,0.0) 100%);
  }
  .decor-othello .arc {
    opacity: 0.26;
    background: radial-gradient(closest-side, transparent calc(50% - 2px), rgba(120,190,255,0.95) calc(50% - 2px) calc(50% + 2px), transparent calc(50% + 2px));
  }
}

@keyframes drift {
  0%   { transform: translate(-50%, -50%) rotate(var(--rot, 0deg)); }
  50%  { transform: translate(calc(-50% + 8px), calc(-50% - 4px)) rotate(calc(var(--rot, 0deg) + 2deg)); }
  100% { transform: translate(calc(-50% - 10px), calc(-50% + 6px)) rotate(calc(var(--rot, 0deg) - 2deg)); }
}
@keyframes pan {
  0% { background-position: 0 0; }
  100% { background-position: 100% 0; }
}
@keyframes spin {
  from { transform: translate(-50%, -50%) rotate(0deg); }
  to   { transform: translate(-50%, -50%) rotate(360deg); }
}

/* motion reduction */
@media (prefers-reduced-motion: reduce) {
  .decor-bubbles span { animation: none; opacity: 0.0; display: none; }
  .decor-othello .orb { animation: none; }
  .decor-othello .rail { animation: none; }
  .decor-othello .arc { animation: none; }
  .disc.place::before { animation: none; opacity: 0; }
  .disc.colorflip::after { animation: none; opacity: 0; }
}

/* ------------------------------- */
/* Subtle Scrollbar Styling        */
/* ------------------------------- */
.sidebar, #move-list {
  scrollbar-width: thin; /* Firefox */
  scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
}

.sidebar::-webkit-scrollbar, #move-list::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}
.sidebar::-webkit-scrollbar-track, #move-list::-webkit-scrollbar-track {
  background: var(--scrollbar-track);
  border-radius: 8px;
}
.sidebar::-webkit-scrollbar-thumb, #move-list::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: 8px;
  border: 2px solid transparent;
  background-clip: padding-box;
}
.sidebar::-webkit-scrollbar-thumb:hover, #move-list::-webkit-scrollbar-thumb:hover {
  background: var(--scrollbar-thumb-hover);
}

/* ---------------------------------- */
/* Coordinate Popup (right-click cell) */
/* ---------------------------------- */
.coord-popup {
  position: fixed;
  z-index: 3000;
  display: none;
  padding: 10px 12px;
  border-radius: 12px;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  box-shadow: var(--panel-shadow);
  backdrop-filter: blur(14px) saturate(1.1);
  color: var(--text-strong);
  min-width: 104px;
  user-select: none;
  -webkit-user-select: none;
  overflow: hidden;
}
.coord-popup.show { display: block; animation: panelIn var(--mid) var(--ease) both; }
.coord-popup::after {
  content: '';
  position: absolute; left: 0; right: 0; top: 0; height: 2px;
  background: linear-gradient(90deg, var(--accent), transparent 60%);
  border-top-left-radius: 12px; border-top-right-radius: 12px;
  pointer-events: none;
}
.coord-popup .coord-title {
  font-size: 0.72rem;
  color: var(--text-dim);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 0 0 6px;
}
.coord-popup .coord-value {
  font-size: 1.24rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--accent-strong);
}