:root{--b:#0277bd;--l:#e1f5fe;--t:#12324a;--g:#2e7d32}
*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,"PingFang SC","Noto Sans SC",sans-serif;color:var(--t);background:#f4fbff;padding-bottom:140px}
.top{position:sticky;top:0;z-index:5;display:flex;align-items:center;gap:8px;background:var(--b);color:#fff;padding:10px 12px}
.top h1{font-size:18px;margin:0;flex:1}.icon{background:none;border:0;color:#fff;font-size:28px;line-height:1;padding:0 6px}
#lang{border-radius:8px;border:0;padding:4px}
.strokes{display:flex;gap:6px;padding:8px;overflow-x:auto;background:#fff;position:sticky;top:48px;z-index:4;box-shadow:0 1px 4px #0001}
.strokes a{flex:1;text-align:center;padding:8px 6px;border-radius:20px;background:var(--l);color:var(--b);text-decoration:none;white-space:nowrap;font-weight:600;font-size:15px}
.strokes a.on{background:var(--b);color:#fff}
main{padding:12px;max-width:720px;margin:auto}
.card{background:#fff;border-radius:14px;padding:14px;margin-bottom:12px;box-shadow:0 1px 4px #0001}
.card h2{margin:0 0 8px;font-size:18px}.card h3{margin:0 0 6px;font-size:16px;color:var(--b)}
.card ul{margin:4px 0;padding-inline-start:20px}.card li{margin:3px 0}
.diagram{width:100%;height:auto;background:linear-gradient(#bfe9ff,#7cc8f0);border-radius:12px}
.btn{display:inline-block;border:0;border-radius:10px;padding:10px 14px;background:var(--b);color:#fff;font-size:15px;text-decoration:none;margin:4px 4px 0 0}
.btn.alt{background:var(--l);color:var(--b)}.btn.ok{background:var(--g)}
.done{color:var(--g);font-weight:600}
.timer{font-size:48px;text-align:center;font-variant-numeric:tabular-nums;margin:8px 0}
.stat{display:flex;gap:8px}.stat div{flex:1;background:var(--l);border-radius:12px;padding:10px;text-align:center}.stat b{display:block;font-size:24px}
.bar{height:8px;background:#e0e0e0;border-radius:4px;overflow:hidden}.bar i{display:block;height:100%;background:var(--b)}
.note{background:#fff8e1;color:#795548;padding:6px 12px;font-size:13px}
.tabs{position:fixed;bottom:0;left:0;right:0;display:flex;background:#fff;border-top:1px solid #ddd;z-index:6}
.tabs a{flex:1;text-align:center;padding:6px 0 8px;color:#678;text-decoration:none;font-size:12px}.tabs a span{display:block;font-size:20px}.tabs a.on{color:var(--b)}
.foot{font-size:12px;color:#678;text-align:center;padding:8px 16px 70px}
[dir=rtl] .icon{transform:scaleX(-1)}