:root{
  --gap:4px;
  --board-max-width:640px;
  --cell: calc((min(100vw, var(--board-max-width)) - 40px - (7 * var(--gap))) / 8);
  --board-padding: var(--gap);
  --control-gap:10px;
  --font-base: 16px;
  --accent: #0b6b3a;
  --bg: #f5f7fa;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Hiragino Kaku Gothic ProN", "Noto Sans JP";
  display:flex; flex-direction:column; align-items:center; padding:16px; margin:0;
  background:var(--bg); color:#222; -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  font-size:var(--font-base);
}

/* 大きなタイトル（レスポンシブ） */
h1{
  margin: 8px 0 14px 0;
  font-size: clamp(1.4rem, 4.5vw, 2.4rem);
  line-height: 1.05;
  font-weight: 700;
  letter-spacing: -0.02em;
  text-align: center;
  color:#000000;
  text-shadow: 0 1px 0 rgba(255,255,255,0.25);
}

/* サブタイトル（任意） */
h1 + .subtitle{
  margin-top:6px;
  font-size:0.95rem;
  color:#3b5f48;
  opacity:0.95;
  text-align:center;
}

/* コントロール */
#controls{
  display:flex; gap:var(--control-gap); align-items:center; margin-bottom:10px; flex-wrap:wrap;
  width:100%; max-width:var(--board-max-width); justify-content:center;
}
.control-group{display:flex;align-items:center;gap:8px;}
.label{font-size:0.95rem;color:#333;margin-right:6px;}
.small{font-size:0.95rem;color:#444;}

/* ボード */
#board{
  display:grid;
  grid-template-columns: repeat(8, var(--cell));
  gap:var(--gap);
  background:var(--accent);
  padding:var(--board-padding);
  border-radius:8px;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  width: calc(var(--cell) * 8 + var(--gap) * 7 + var(--board-padding) * 2);
  max-width:100%;
  transition: opacity .18s ease;
}

/* セル */
.cell{
  width:var(--cell);
  height:var(--cell);
  background:#2e8b57;
  border-radius:4px;
  position:relative;
  cursor:pointer;
  box-shadow:inset 0 -2px 0 rgba(0,0,0,0.15);
  user-select:none;
  -webkit-user-select:none;
  display:flex; align-items:center; justify-content:center;
  -webkit-tap-highlight-color: transparent;
}
.cell.disabled{cursor:default; opacity:0.95;}
.cell:active{transform:scale(0.995);}

/* 石 */
.disc{position:absolute; inset:6px; border-radius:50%; transition:transform .18s ease, background .18s ease; transform:scale(1); display:flex; align-items:center; justify-content:center;}
.black{background:#111; box-shadow:0 2px 0 rgba(0,0,0,0.4);}
.white{background:#fff; box-shadow:0 2px 0 rgba(0,0,0,0.15);}

/* ヒント（合法手） */
.hint::after{content:""; position:absolute; inset:14px; border-radius:50%; background:rgba(255,255,255,0.25);}

/* 情報領域 */
#info{margin-top:12px; display:flex; gap:12px; align-items:center; flex-wrap:wrap; width:100%; max-width:var(--board-max-width); justify-content:center;}
#score{font-weight:600;}
#status{min-width:220px; text-align:center;}

/* コントロールのタッチ領域を広げる */
button, select, input[type="range"]{
  padding:10px 12px; border-radius:8px; border:1px solid #ccc; background:#fff; cursor:pointer;
  -webkit-tap-highlight-color: transparent;
}
button{min-height:44px;}

/* ゲームオーバー時の視覚変化 */
#board.game-over{opacity:0.98; filter:grayscale(0.02);}

/* レスポンシブ調整 */
@media (max-width:420px){
  :root{
    --gap:3px;
    --font-base:15px;
    --cell: calc((100vw - 32px - (7 * var(--gap))) / 8);
  }
  #controls{gap:8px; padding:0 4px;}
  .control-group{flex:1 1 100%; justify-content:space-between;}
  .label{font-size:0.85rem;}
  .small{font-size:0.85rem;}
  #status{min-width:160px;}
}

/* 横向き（ランドスケープ）で盤を大きく */
@media (orientation:landscape) and (max-height:420px){
  :root{
    --cell: calc((100vh - 48px - (7 * var(--gap))) / 8);
  }
}

/* アクセシビリティ補助（フォーカス可視化） */
.cell:focus{outline:3px solid rgba(255,255,255,0.12); outline-offset:2px;}
button:focus, select:focus, input[type="range"]:focus{outline:3px solid rgba(11,107,58,0.12); outline-offset:2px;}