:root{--bg:#0d2b3f;--ink:#1d2b2a;--accent:#24564f;--card:#fffdf7;--line:#ddd8c8}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:system-ui,-apple-system,"Hiragino Sans","Noto Sans JP",sans-serif;
  -webkit-tap-highlight-color:transparent;overflow:hidden;overscroll-behavior:none}
.stage{height:100dvh;display:flex;align-items:center;justify-content:center}
#board{width:min(100vw,calc(100dvh*360/640));height:auto;aspect-ratio:360/640;display:block;touch-action:manipulation;user-select:none;-webkit-user-select:none}
button{font:inherit;color:inherit;cursor:pointer}
.menu{position:fixed;top:calc(env(safe-area-inset-top) + 8px);right:8px;z-index:30;width:42px;height:42px;border:0;border-radius:12px;
  background:rgba(13,43,63,.72);color:#fff;font-size:20px;line-height:1}
.toast{position:fixed;left:50%;top:46%;transform:translate(-50%,-50%);z-index:25;margin:0;padding:14px 22px;border-radius:14px;
  background:rgba(255,253,247,.95);font-size:24px;font-weight:bold;white-space:nowrap;pointer-events:none;box-shadow:0 6px 24px rgba(0,0,0,.25)}
.toast.small{font-size:16px}
.toast.mirrored{transform:translate(-50%,-50%) scaleX(-1)}
.toast[hidden],.backdrop[hidden],.dialog[hidden],.sheet[hidden]{display:none}
.backdrop{position:fixed;inset:0;z-index:26;background:rgba(0,0,0,.45)}
.dialog{position:fixed;z-index:27;left:50%;top:50%;transform:translate(-50%,-50%);width:min(92vw,380px);max-height:86dvh;overflow:auto;
  background:var(--card);border-radius:16px;padding:20px 18px;box-shadow:0 10px 40px rgba(0,0,0,.35)}
.dialog h1{font-size:22px;margin:0 0 6px;text-align:center}
.dialog h2{font-size:18px;margin:0 0 10px}
.lead{text-align:center;margin:0 0 12px;font-size:16px}
.legend{display:flex;gap:8px;justify-content:center;margin:0 0 12px}
.legend figure{margin:0;text-align:center;background:#e8f2f6;border-radius:12px;padding:6px 4px}
.legend canvas{width:120px;height:64px;display:block}
.legend figcaption{font-weight:bold;font-size:15px}
.notes{padding-left:1.2em;margin:0 0 14px;font-size:13px;line-height:1.6}
.primary{display:block;width:100%;border:0;border-radius:12px;padding:13px;background:var(--accent);color:#fff;font-size:17px;font-weight:bold}
.secondary{display:block;width:100%;border:1px solid var(--line);border-radius:12px;padding:12px;background:#fff;font-size:16px;text-align:center;text-decoration:none;color:var(--ink);margin-top:8px}
.menu-items .secondary:first-child{margin-top:0}
.hint{font-size:16px;line-height:1.7;margin:0 0 12px}
.stats{width:100%;border-collapse:collapse;font-size:15px;margin-bottom:12px}
.stats th,.stats td{padding:7px 4px;border-bottom:1px solid var(--line);text-align:right}
.stats th{text-align:left;font-weight:normal}
.sheet{position:fixed;inset:0;z-index:22;display:flex;align-items:center;justify-content:center;background:rgba(0,0,0,.4)}
.card{width:min(90vw,360px);background:var(--card);border-radius:18px;padding:24px 18px;text-align:center;box-shadow:0 10px 40px rgba(0,0,0,.35)}
.big{font-size:28px;font-weight:bold;margin:6px 0 18px}
.row{display:flex;gap:8px;margin-bottom:8px}
.row button,.row .btn{flex:1;border:1px solid var(--line);border-radius:12px;padding:11px;background:#fff;font-size:16px;color:inherit;text-align:center;text-decoration:none}
.url{font-size:13px;opacity:.7;margin:-4px 0 10px;word-break:break-all}
.mirrored{transform:scaleX(-1)}
.flip{margin-top:12px;border:0;background:none;text-decoration:underline;font-size:14px;color:#555}
.flip[hidden]{display:none}
.hints{font-size:16px;line-height:1.7;margin:0 0 12px;padding-left:1.4em;text-align:left}
.hints li+li{margin-top:6px}