:root{color-scheme:light;--ink:#24384d;--muted:#73808d;--blue:#305e92;--line:#dbe2e9}*{box-sizing:border-box}body{margin:0;background:#eef2f6;color:var(--ink);font:15px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}button,select,input{font:inherit;color:inherit}button{cursor:pointer;background:white;border:1px solid var(--line);border-radius:8px;padding:7px 13px}button:hover{border-color:#829bb6}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #759bd0;outline-offset:2px}button:disabled{opacity:.45;cursor:default}button[aria-pressed=true]{background:var(--blue);border-color:var(--blue);color:#fff}a{color:var(--blue);text-decoration:none}.top{max-width:1160px;margin:auto;display:flex;align-items:center;justify-content:space-between;padding:22px 24px;gap:12px}.top h1{font-size:25px;letter-spacing:-1px;margin:0}.top>div{display:flex;align-items:center;gap:10px}.version{font-size:11px;color:var(--muted)}main{max-width:1160px;margin:0 auto 36px;display:grid;grid-template-columns:minmax(0,660px) minmax(0,380px);gap:28px;padding:0 24px}.table{min-width:0}.modes{display:flex;gap:7px;margin-bottom:13px}.modes button{flex:1}.board-top{display:flex;align-items:center;justify-content:space-between;padding:7px 3px 12px}.board-top label{color:var(--muted);font-size:13px}select{background:#fff;border:1px solid var(--line);padding:4px 7px;border-radius:6px}#board{position:relative;width:100%;aspect-ratio:9/10;background:linear-gradient(125deg,#f4dfb6,#e8c991);border:7px solid #987348;border-radius:10px;box-shadow:0 9px 25px #24384d19;overflow:hidden}#grid,#overlay,#squares{position:absolute;inset:0;width:100%;height:100%}#overlay{pointer-events:none;overflow:visible}#grid line{stroke:#866541;stroke-width:2.3}#grid text{fill:#866541;font-family:serif;font-size:37px;letter-spacing:10px}#squares button{position:absolute;transform:translate(-50%,-50%);padding:0;width:10.6%;height:9.5%;background:none;border:0;border-radius:50%;display:grid;place-items:center;touch-action:manipulation}#squares button::after{content:"";width:19%;aspect-ratio:1;position:absolute;border-radius:50%;background:transparent}#squares button.legal::after{background:#325f94aa}#squares button.legal:has(.piece)::after{width:97%;background:none;border:4px solid #325f94aa}#squares button.last{background:#ffed8980}#squares button.selected{box-shadow:0 0 0 3px #305e92}#squares button.check{box-shadow:0 0 0 3px #d03435}.piece{display:grid;place-items:center;width:87%;aspect-ratio:1;border-radius:50%;background:radial-gradient(circle at 35% 25%,#fff6dc,#ebc789);box-shadow:0 3px 4px #6b411963,inset 0 0 0 2px #ac8655,inset 0 0 0 5px #f9e5b9,inset 0 0 0 6px currentColor;color:#263340;font:bold clamp(20px,3vw,40px)/1 "Songti SC","Noto Serif CJK SC",serif;pointer-events:none}.piece.red{color:#b82d28}.move-arrow{stroke:#2f689bcc;stroke-width:8;stroke-linecap:round}.controls{display:flex;gap:8px;margin-top:16px}.controls button{flex:1}#message{min-height:24px;margin:10px 3px;color:var(--blue);font-size:14px}.lesson,.library{background:#fff;border:1px solid var(--line);border-radius:12px;padding:20px;margin-bottom:18px}.eyebrow{font-size:12px;color:var(--muted)}h2{font-size:21px;margin:5px 0 12px;line-height:1.4}h3{font-size:12px;font-weight:600;color:var(--muted);margin:18px 0 4px}p{margin:6px 0 10px}.progress{display:flex;justify-content:space-between;gap:8px;color:var(--muted);font-size:12px}.track{height:4px;background:#e8edf3;margin:10px 0 15px;border-radius:5px;overflow:hidden}.track i{display:block;height:100%;background:var(--blue);transition:width .2s}#explanation{font-weight:500;min-height:45px}#plans p{font-size:14px}details{border-top:1px solid var(--line);padding-top:11px;margin-top:15px;font-size:13px}summary{cursor:pointer;color:var(--muted)}#moves{display:grid;grid-template-columns:1fr 1fr;gap:4px 22px;padding-left:24px;max-height:160px;overflow:auto}#rulesNote{font-size:12px;color:var(--muted);margin-top:10px}#completion{display:flex;flex-wrap:wrap;gap:6px;margin:15px 0}[hidden]{display:none!important}.library-head{display:flex;align-items:center;justify-content:space-between}.library-head h2{font-size:18px}#count{font-size:12px;color:var(--muted)}#search{width:100%;background:#f6f8fb;border:1px solid var(--line);border-radius:7px;padding:8px 10px}.filters{display:flex;gap:5px;margin:12px 0}.filters button{padding:5px 10px;font-size:12px}#courses{max-height:325px;overflow:auto;display:grid;gap:5px}#courses button{display:flex;align-items:center;justify-content:space-between;text-align:left;padding:11px 10px;font-size:14px}#courses small{font-size:11px;opacity:.65;white-space:nowrap;margin-left:6px}.empty{color:var(--muted);font-size:13px;padding:10px}@media(min-width:1100px){.table{position:sticky;top:16px;align-self:start}}@media(max-width:800px){main{grid-template-columns:minmax(0,1fr);max-width:600px;gap:8px;padding:0 14px}.top{padding:16px 14px;max-width:600px}.top h1{font-size:21px}.top>a{font-size:13px}.piece{font-size:clamp(20px,6vw,37px)}.lesson,.library{padding:17px}.modes button{padding:7px 6px;font-size:14px}#board{border-width:5px}.table{position:static}#courses{max-height:360px}}@media(prefers-reduced-motion:reduce){*{transition:none!important}}

#startRandom{background:var(--blue);border-color:var(--blue);color:white;font-size:13px;padding:6px 12px}.board-top{gap:8px}

.position-link{display:grid;place-items:center;padding:7px 12px;border:1px solid var(--line);border-radius:8px;background:white;font-size:14px}.modes{align-items:stretch}

#difficultyWrap{margin-top:12px;font-size:13px;color:var(--muted)}#difficultyWrap label{display:flex;gap:10px;align-items:center}

@media(max-width:480px){.modes{flex-wrap:wrap}.modes button{flex:1 1 20%}.modes .position-link{flex:1 1 40%}}