:root{color-scheme:light;--bg:#faf7ef;--panel:#fff;--panel2:#f1ece0;--ink:#231f18;--muted:#7a7263;--faint:#b9af9c;--line:rgba(35,31,24,.09);--accent:#3f6b52;--accent2:#b5652f;--accent-soft:#e7eee3;--danger:#b23a2e;--on-accent:#fff;--shadow:0 7px 22px rgba(44,38,25,.055);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",system-ui,sans-serif}
html[data-theme=dark]{color-scheme:dark;--bg:#15140f;--panel:#201e17;--panel2:#2a2820;--ink:#f3efe4;--muted:#9b937f;--faint:#5c574a;--line:rgba(243,239,228,.09);--accent:#6fa383;--accent2:#d68a54;--accent-soft:rgba(111,163,131,.18);--danger:#e0685a;--on-accent:#15140f;--shadow:none}
*{box-sizing:border-box}body{margin:0;min-width:320px;background:var(--bg);color:var(--ink);-webkit-tap-highlight-color:transparent}.app-shell{width:100%;max-width:428px;min-height:100dvh;margin:auto;padding:env(safe-area-inset-top) 0 calc(84px + env(safe-area-inset-bottom));background:var(--bg)}.app-header{position:sticky;top:0;z-index:20;height:68px;padding:0 20px;display:flex;align-items:center;justify-content:space-between;background:color-mix(in srgb,var(--bg) 88%,transparent);border-bottom:1px solid var(--line);backdrop-filter:blur(12px)}.brand{display:flex;align-items:center;gap:8px;color:inherit;text-decoration:none;font:600 21px/1 "Source Serif 4",Georgia,serif}.brand img{width:22px;height:22px;opacity:.82}.icon-button{width:36px;height:36px;border:1px solid var(--line);border-radius:50%;background:var(--panel);color:var(--muted);display:grid;place-items:center;cursor:pointer}.icon-button:before{content:"☾";font-size:18px}.icon-button:focus-visible,.button:focus-visible,.row-card:focus-visible,.tab:focus-visible,.chip:focus-visible,.square:focus-visible{outline:3px solid var(--accent2);outline-offset:2px}
#app{min-height:calc(100dvh - 152px);padding:14px 20px 20px;animation:rise .25s ease both}h1,h2,h3,p{margin-top:0}h1,h2{font-family:"Source Serif 4",Georgia,serif;letter-spacing:-.02em}h1{font-size:30px;line-height:1.12;font-weight:600;margin-bottom:4px}h2{font-size:21px;line-height:1.2;font-weight:600;margin-bottom:7px}h3{font-size:15px;margin-bottom:4px}.lede{margin:0 0 21px;color:var(--muted);font-size:15px;line-height:1.5}.eyebrow,.section-label{font-size:12px;font-weight:700;letter-spacing:.07em;text-transform:uppercase;color:var(--muted)}.section{margin-top:25px}.section-title{display:flex;justify-content:space-between;align-items:center;margin:0 0 10px}.section-title a,.text-button{border:0;background:none;padding:0;color:var(--accent);font-size:13px;font-weight:700;cursor:pointer;text-decoration:none}.card,.row-card{background:var(--panel);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow)}.card{padding:16px}.row-list{display:grid;gap:10px}.row-card{display:flex;width:100%;align-items:center;gap:14px;padding:17px;text-align:left;color:inherit;cursor:pointer}.row-icon{width:44px;height:44px;border-radius:12px;flex:none;display:grid;place-items:center;background:var(--accent-soft);color:var(--accent);font-size:21px;font-family:"Source Serif 4",Georgia,serif}.row-copy{flex:1;min-width:0}.row-copy strong{display:block;font-size:16px}.row-copy small{display:block;margin-top:3px;color:var(--muted);font-size:13px;line-height:1.35}.chev{font-size:23px;color:var(--faint)}.button{border:0;border-radius:14px;min-height:48px;padding:0 17px;background:var(--accent);color:var(--on-accent);font-weight:700;font-size:15px;cursor:pointer}.button.secondary{border:1px solid var(--line);background:var(--panel);color:var(--ink)}.button.danger{border:1px solid var(--line);background:var(--panel);color:var(--danger)}.button:disabled{opacity:.4;cursor:not-allowed}.button.full{width:100%}.pill,.chip{display:inline-block;border:1px solid var(--line);border-radius:999px;background:var(--panel2);padding:5px 9px;color:var(--muted);font-size:12px;font-weight:700}.chip{background:var(--panel);color:var(--ink);cursor:pointer}.chip.active{background:var(--accent);border-color:var(--accent);color:var(--on-accent)}.chip-row{display:flex;gap:7px;overflow-x:auto;padding:2px 0 6px;scrollbar-width:none}.chip-row::-webkit-scrollbar{display:none}.choice-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin:8px 0 23px}.choice-grid.three{grid-template-columns:repeat(3,1fr)}.choice{min-height:46px;border-radius:12px;border:1px solid var(--line);background:var(--panel);color:var(--ink);font-weight:700;cursor:pointer}.choice.active{border-color:var(--accent);background:var(--accent-soft);color:var(--accent)}.choice .piece-mini{display:block;width:20px;height:20px;margin:0 auto 2px}.board-tools{width:100%;display:flex;align-items:center;justify-content:space-between;margin:2px 0 2px}.swatches{display:flex;gap:7px}.swatch{width:22px;height:22px;padding:0;border:2px solid var(--panel);border-radius:50%;cursor:pointer;box-shadow:0 0 0 1px var(--line)}.swatch.active{box-shadow:0 0 0 2px var(--accent)}.flip{width:34px;height:34px;border-radius:50%;border:1px solid var(--line);background:var(--panel);color:var(--ink);cursor:pointer;font-size:17px}.board-wrap{width:100%;max-width:380px;margin:0 auto}.player-bar{width:100%;max-width:380px;margin:10px auto;padding:10px 15px;display:flex;justify-content:space-between;align-items:center;border:1px solid var(--line);border-radius:14px;background:var(--panel)}.player-bar strong:last-child{font-variant-numeric:tabular-nums;font-size:17px}.player-bar.active{color:var(--accent);border-color:color-mix(in srgb,var(--accent) 34%,var(--line))}.board{width:100%;aspect-ratio:1;display:grid;grid-template-columns:repeat(8,1fr);overflow:hidden;border-radius:18px;box-shadow:var(--shadow)}.square{border:0;position:relative;display:grid;place-items:center;padding:0;cursor:pointer;background:#f4efe2;isolation:isolate}.square.dark{background:#9cb18f}.square.selected:before,.square.last:before{content:"";position:absolute;inset:0;background:rgba(244,201,58,.48);z-index:-1}.square.hint:after{content:"";position:absolute;width:27%;aspect-ratio:1;border-radius:50%;background:rgba(36,67,45,.45)}.square.hint.has-piece:after{width:87%;height:87%;border:3px solid rgba(36,67,45,.52);background:transparent}.piece{width:84%;height:84%;object-fit:contain;z-index:1;pointer-events:none;filter:drop-shadow(0 1px 1px rgba(0,0,0,.16))}.rank-label,.file-label{position:absolute;z-index:2;font-size:10px;font-weight:800;line-height:1;pointer-events:none;color:#78916c}.square.dark .rank-label,.square.dark .file-label{color:#edf1dc}.rank-label{top:4px;left:5px}.file-label{right:5px;bottom:4px}.coords{display:flex;justify-content:space-between;color:var(--faint);font-size:11px;margin:5px 3px 0}.note{margin-top:15px}.note p{margin:7px 0 0;font-size:14px;color:var(--muted);line-height:1.5}.actions{display:flex;gap:8px;margin-top:14px}.actions .button{flex:1}.feedback{margin-top:12px;border-radius:12px;padding:12px 14px;font-weight:650;font-size:14px}.feedback.good{background:var(--accent-soft);color:var(--accent)}.feedback.bad{background:color-mix(in srgb,var(--danger) 12%,var(--panel));color:var(--danger)}.key-ideas{margin:17px 0 0;padding-left:19px;color:var(--muted);font-size:14px;line-height:1.55}.key-ideas li+li{margin-top:5px}.move-strip{display:flex;gap:7px;overflow:auto;margin-top:14px;padding:2px 0}.move-chip{white-space:nowrap;border:1px solid var(--line);border-radius:9px;padding:7px 9px;background:var(--panel2);font-size:12px}.move-chip.current{background:var(--accent);border-color:var(--accent);color:var(--on-accent);font-weight:700}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:9px}.stat{text-align:center;padding:14px 8px}.stat strong{display:block;font:600 26px/1 "Source Serif 4",Georgia,serif;color:var(--accent)}.stat span{font-size:11px;color:var(--muted)}.empty{padding:20px;text-align:center;border:1px dashed var(--line);border-radius:16px;color:var(--muted);font-size:14px;line-height:1.45}.tabbar{position:fixed;z-index:30;left:0;right:0;bottom:0;max-width:428px;margin:auto;height:70px;padding:6px 8px calc(6px + env(safe-area-inset-bottom));display:flex;justify-content:space-around;background:color-mix(in srgb,var(--bg) 89%,transparent);border-top:1px solid var(--line);backdrop-filter:blur(15px)}.tab{flex:1;border:0;border-radius:12px;background:transparent;color:var(--faint);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;font-size:10px;font-weight:700;cursor:pointer}.tab span{font-size:21px;line-height:19px}.tab.active{color:var(--accent);background:var(--accent-soft)}.toast{position:fixed;z-index:60;left:50%;bottom:84px;transform:translate(-50%,12px);opacity:0;transition:.2s;background:var(--ink);color:var(--bg);padding:10px 14px;border-radius:12px;font-weight:650;font-size:13px;max-width:calc(100% - 32px);text-align:center;pointer-events:none}.toast.show{opacity:1;transform:translate(-50%,0)}.hidden{display:none}@keyframes rise{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}@media(min-width:429px){body{background:#e8e4d9}.app-shell{box-shadow:0 0 60px rgba(0,0,0,.1)}html[data-theme=dark] body{background:#0b0b09}}