:root{color-scheme:dark;--bg:#111425;--panel:#1c2136;--input:#101528;--text:#f5f5fb;--muted:#c3cbdf;--line:#505d7b;--accent:#e0d4ff;--ink:#201439;--success:#b9eed3;--error:#ffd1ce;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;font-size:16px;line-height:1.6}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text)}button,input,textarea,select{font:inherit}button,a,input,textarea,select,summary{touch-action:manipulation}a{color:var(--accent);text-underline-offset:4px}button{cursor:pointer;border:1px solid var(--line);border-radius:10px;padding:11px 18px;min-height:46px;background:#2a334d;color:var(--text);font-weight:650}button:hover{background:#394565}button:disabled{cursor:wait}button.primary,.primary{background:var(--accent);color:var(--ink);border-color:var(--accent)}button.primary:hover{background:#efe7ff}.quiet{background:var(--panel)}:focus-visible{outline:3px solid #ffe19a;outline-offset:4px}.site-header{max-width:1248px;padding:24px;display:flex;align-items:center;justify-content:space-between;gap:12px;margin:auto}.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font-size:20px;font-weight:760;color:var(--text)}.brand-icon{display:grid;place-items:center;width:33px;height:33px;border:2px solid var(--accent);color:var(--accent);border-radius:8px;font-size:19px}.lab{font-size:12px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);margin-left:8px}main{max-width:1200px;margin:0 auto;padding:24px 24px 48px;min-height:65vh}h1{font-size:clamp(2rem,5vw,3.7rem);letter-spacing:-.04em;line-height:1.09;margin:12px 0 22px;max-width:800px}h2{font-size:1.45rem;line-height:1.3;letter-spacing:-.02em;margin:0 0 16px}h3{font-size:1.05rem;margin:20px 0 8px}p{margin:0 0 16px}.eyebrow{font-size:.77rem;text-transform:uppercase;letter-spacing:.13em;color:var(--accent);font-weight:700}.lede{font-size:1.15rem;color:var(--muted);max-width:720px}.pills{display:flex;flex-wrap:wrap;gap:8px;margin:24px 0 32px}.pill{padding:5px 12px;border:1px solid var(--line);border-radius:99px;background:var(--panel);font-size:.86rem}.intro-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px;align-items:start}.panel{border:1px solid var(--line);border-radius:18px;background:var(--panel);padding:28px}.steps{padding-left:24px;margin:0}.steps li{padding-left:8px;margin:0 0 18px}.steps li:last-child{margin-bottom:0}.steps strong{display:block}.muted,small,.hint{color:var(--muted)}small,.hint{font-size:.87rem;line-height:1.5}.hint{margin:8px 0 16px}.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}.field{margin:0 0 18px;min-width:0}.field label{display:block;font-weight:650;margin-bottom:7px}input:not([type=checkbox]),select,textarea{width:100%;border:1px solid #8593b1;border-radius:8px;padding:11px 12px;background:var(--input);color:var(--text);min-height:46px}textarea{min-height:280px;resize:vertical;line-height:1.6}::placeholder{color:#bdc6dc;opacity:1}.check{display:flex;gap:12px;align-items:start;font-size:.9rem;margin:8px 0 22px}.check input{width:20px;height:20px;min-width:20px;margin-top:4px;accent-color:#ddceff}.actions{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin-top:20px}.actions button{flex-grow:0}.wide{width:100%}.error{color:var(--error);background:#3c222d;border:1px solid #d9a09d;border-radius:8px;padding:12px;margin:16px 0}.success{color:var(--success)}.position-header{display:flex;gap:20px;align-items:start;justify-content:space-between;margin-bottom:24px}.position-header h1{font-size:clamp(1.8rem,4vw,2.6rem);margin-bottom:8px}.progress{display:flex;gap:6px;margin-top:12px}.progress span{height:5px;width:34px;background:#58617d;border-radius:4px}.progress .done{background:#afe6ca}.progress .current{background:var(--accent)}.exercise{display:grid;grid-template-columns:minmax(280px,1fr) minmax(320px,1.05fr);gap:28px;align-items:start}.board-panel{position:sticky;top:20px}.board-heading{display:flex;justify-content:space-between;gap:12px;align-items:center;margin-bottom:12px;font-size:.9rem}.turn{display:flex;gap:8px;align-items:center}.white-dot{width:13px;height:13px;border-radius:50%;background:#fff;border:1px solid #444}.board-frame{display:grid;grid-template-columns:20px 1fr;grid-template-rows:1fr 20px;gap:5px}.ranks{display:grid;grid-template-rows:repeat(8,1fr);align-items:center;text-align:center;font-size:12px;color:var(--muted)}.files{grid-column:2;display:grid;grid-template-columns:repeat(8,1fr);text-align:center;font-size:12px;color:var(--muted)}.board{display:grid;grid-template-columns:repeat(8,1fr);aspect-ratio:1;overflow:hidden;border:1px solid #b6bfd6;border-radius:3px;background:#e0d6c7}.sq{display:grid;place-items:center;aspect-ratio:1;background:#e0d6c7}.sq.dark{background:#788d96}.sq img{width:91%;height:91%;display:block;object-fit:contain;user-select:none;-webkit-user-drag:none}details{margin-top:18px}summary{cursor:pointer;color:var(--accent);font-weight:650}details p,details ul{margin-top:12px}.compact{font-size:.9rem}.answer-panel{padding:24px}.answer-panel textarea{min-height:320px}.answer-panel h2{font-size:1.35rem}fieldset{border:0;padding:0;margin:0;min-width:0}legend{font-size:1.12rem;font-weight:700;padding:0 0 18px}.after{margin-top:22px;padding-top:22px;border-top:1px solid var(--line)}.storage-note{border-left:3px solid var(--accent);padding-left:12px;color:var(--muted);font-size:.85rem;margin-top:16px}.end{max-width:760px;margin:auto}.end h1{font-size:clamp(2rem,5vw,3rem)}.receipt{font-family:ui-monospace,monospace;overflow-wrap:anywhere;background:var(--input);padding:12px;border-radius:8px;font-size:.82rem}.notice{position:fixed;bottom:20px;left:50%;transform:translateX(-50%);width:max-content;max-width:calc(100% - 32px);background:#243e36;color:#d5ffdf;border:1px solid #a7dcc1;padding:12px 20px;border-radius:10px;z-index:20;box-shadow:0 4px 24px #0006}footer{max-width:1200px;margin:auto;padding:24px;border-top:1px solid var(--line);color:var(--muted);font-size:.85rem;display:flex;flex-wrap:wrap;gap:12px 24px}footer p{flex-basis:100%;margin:4px 0}.skip{position:absolute;left:12px;top:-100px;background:var(--panel);padding:12px;z-index:30}.skip:focus{top:12px}[hidden]{display:none!important}.import-label{display:inline-flex;cursor:pointer;align-items:center;border:1px solid var(--line);background:#2a334d;color:var(--text);border-radius:10px;padding:11px 18px;min-height:46px;font-weight:650}.import-label:focus-within{outline:3px solid #ffe19a;outline-offset:4px}.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
@media(max-width:800px){.intro-grid{grid-template-columns:1fr}.exercise{grid-template-columns:1fr}.board-panel{position:static;max-width:520px;width:100%;margin:auto}.answer-panel{padding:22px}.position-header{gap:12px}.position-header .quiet{font-size:.85rem;padding:9px 12px}main{padding-top:16px}}@media(max-width:440px){.site-header{padding:18px 16px}.brand{font-size:18px;gap:8px}.lab{display:none}main{padding:16px 16px 32px}.panel{padding:22px 18px}.form-grid{grid-template-columns:1fr;gap:0}.pills{gap:6px;margin:20px 0 26px}.pill{font-size:.78rem;padding:4px 10px}h1{margin-top:10px}.actions button{width:100%}.answer-panel textarea{min-height:280px}.progress span{width:28px}}