:root{color-scheme:light;--paper:#f4f1e9;--ink:#202d29;--muted:#69716a;--line:#d8dcd0;--green:#245744;--light:#ece8d9;--dark:#83988a;--red:#aa3535;--sans:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}
*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:15px;line-height:1.6}button,select{font:inherit}button,select,a{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default}button:focus-visible,select:focus-visible,a:focus-visible{outline:3px solid #bd8430;outline-offset:4px}button[hidden],section[hidden]{display:none!important}.shell{max-width:1200px;margin:auto;padding:0 42px}.masthead{display:flex;align-items:center;justify-content:space-between;padding:27px 0 24px;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-family:Georgia,serif;font-size:27px;letter-spacing:-.7px}.tagline{color:var(--muted);font-size:13px;letter-spacing:.02em}.game-heading{display:flex;justify-content:space-between;align-items:center;gap:24px;margin:38px 0 27px}.eyebrow{font-size:10px;font-weight:700;letter-spacing:1.8px;margin:0 0 7px;color:var(--muted)}h1{font:normal clamp(26px,3.3vw,37px)/1.2 Georgia,serif;letter-spacing:-.8px;margin:0 0 8px}.muted{color:var(--muted);font-size:13px;margin:0}.game-picker{min-width:240px}.game-picker label{display:block;font-size:11px;color:var(--muted);margin-bottom:6px}select{width:100%;max-width:330px;padding:10px 34px 10px 13px;border:1px solid #cdd3c8;background:#faf9f4;color:var(--ink);border-radius:5px;font-size:13px}.trainer{display:grid;grid-template-columns:minmax(0,1.3fr) minmax(300px,1fr);gap:38px;align-items:stretch}.board-panel{min-width:0}.board-toolbar{display:flex;align-items:center;justify-content:space-between;margin-bottom:13px;min-height:34px}.turn{display:flex;gap:9px;align-items:center;font-size:13px;font-weight:600}.turn-dot{width:13px;height:13px;border-radius:50%;border:1px solid #35473e;background:white}.turn-dot.black{background:#26392f}.quiet{border:0;background:transparent;color:var(--green);padding:7px 0;font-size:12px;font-weight:600}.quiet:hover{color:#101e18;text-decoration:underline}.quiet span{font-size:18px;vertical-align:-1px;margin-right:4px}.board{display:grid;grid-template-columns:repeat(8,1fr);aspect-ratio:1;border:7px solid #34483d;border-radius:3px;box-shadow:0 8px 25px #2a39200d;overflow:hidden;touch-action:manipulation}.square{position:relative;display:flex;align-items:center;justify-content:center;padding:0;border:0;border-radius:0;aspect-ratio:1;min-width:0;background:var(--light);color:#334f40;touch-action:manipulation}.square.dark{background:var(--dark);color:#f5f3e9}.square.last{background:#ced39a}.square.dark.last{background:#9eae68}.square.selected{background:#eacb72;box-shadow:inset 0 0 0 3px #91682c}.square:focus-visible{outline:3px solid #b77728;outline-offset:-3px;z-index:2}.square img{width:89%;height:89%;user-select:none;filter:drop-shadow(0 1px 1px #0002);pointer-events:none}.square[draggable=true]{cursor:grab}.square[draggable=true]:active{cursor:grabbing}.square .coordinate{position:absolute;font-size:clamp(9px,1vw,11px);font-weight:650;line-height:1;pointer-events:none}.rank{top:4px;left:4px}.file{right:4px;bottom:3px}.board-caption{display:flex;justify-content:space-between;gap:8px;font-size:10px;color:var(--muted);margin:10px 1px 0}.study-panel{background:#faf9f4;border:1px solid var(--line);border-radius:7px;margin-top:47px;padding:27px 28px 18px;display:flex;flex-direction:column;min-width:0}.progress-heading{display:flex;justify-content:space-between;align-items:baseline;gap:10px}.progress-heading .eyebrow{margin-bottom:9px}#progress-count{font-size:11px;color:var(--muted);white-space:nowrap}progress{appearance:none;width:100%;height:4px;display:block;border:0;background:#e5e7dc;border-radius:5px;overflow:hidden}progress::-webkit-progress-bar{background:#e5e7dc}progress::-webkit-progress-value{background:#48705b;transition:width .25s}progress::-moz-progress-bar{background:#48705b}.feedback{margin-top:31px}.feedback h2{font:normal 28px/1.2 Georgia,serif;letter-spacing:-.4px;margin:0 0 10px}.feedback p{color:var(--muted);font-size:13px;margin:0 0 8px}.feedback .status-icon{display:inline-grid;place-items:center;width:29px;height:29px;border-radius:50%;margin-bottom:17px;background:#e5ebdf;color:var(--green);font-family:var(--sans);font-size:19px;font-weight:700}.feedback.wrong .status-icon{background:#fae5df;color:var(--red)}.feedback.wrong h2{color:var(--red)}.move-label{display:inline-block;margin-top:6px!important;color:var(--green)!important;font-size:20px!important;font-weight:650}#explanation{border-top:1px solid var(--line);padding-top:20px;margin-top:15px}#explanation-text{font-size:15px;line-height:1.75;margin:9px 0 0}.primary-actions{margin-top:23px}.primary{border:1px solid var(--green);border-radius:4px;background:var(--green);color:white;padding:11px 18px;font-size:13px;font-weight:600;display:inline-flex;align-items:center;justify-content:space-between;gap:28px}.primary:hover{background:#193f31}.primary:active{transform:translateY(1px)}.study-bottom{margin-top:auto;padding-top:26px;display:flex;flex-direction:column;align-items:flex-start;gap:11px}.study-bottom p{font-size:12px;color:var(--muted);margin:0}.source-note{margin:24px 0 30px;font-size:11px;color:var(--muted);max-width:600px}footer{display:flex;justify-content:space-between;border-top:1px solid var(--line);padding:18px 0 22px;color:var(--muted);font-size:11px}dialog{max-width:min(420px,90vw);padding:26px;border:1px solid var(--line);border-radius:8px;color:var(--ink);background:#faf9f4}dialog::backdrop{background:#142b2366}dialog h2{font:normal 26px Georgia,serif;margin:0 0 15px}dialog p{font-size:14px;color:var(--muted)}.dialog-actions{display:flex;justify-content:space-between;gap:24px;margin-top:23px}#promotion-options{display:flex;gap:8px;margin-bottom:14px}#promotion-options button{width:66px;padding:8px;background:var(--light);border:1px solid var(--line);border-radius:3px}#promotion-options img{width:100%}noscript{display:block;text-align:center;padding:20px}
@media(min-width:1150px){.trainer{gap:46px}.study-panel{padding:30px 32px 22px}}
@media(max-width:820px){.shell{padding:0 22px}.game-heading{margin-top:28px}.trainer{gap:23px;grid-template-columns:minmax(0,1.2fr) minmax(270px,1fr)}.study-panel{padding:22px 20px 17px}.board-caption{font-size:9px}.tagline{display:none}.game-picker{min-width:220px}}
@media(max-width:650px){.shell{padding:0 18px}.masthead{padding:18px 0}.brand{font-size:25px}.brand img{width:32px;height:32px}.game-heading{flex-direction:column;align-items:stretch;gap:18px;margin:25px 0 20px}.game-picker{min-width:0}.game-picker label{display:none}select{max-width:none}.trainer{grid-template-columns:1fr;gap:20px}.board{border-width:5px}.board-caption{font-size:9px}.study-panel{margin-top:0;min-height:310px;padding:22px}.feedback{margin-top:23px}.feedback h2{font-size:26px}.study-bottom{padding-top:20px}.source-note{margin:20px 0}footer{gap:14px;font-size:10px}.square .coordinate{font-size:10px}#next,#again{width:100%}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}