:root{color-scheme:dark;--bg:#101c1b;--panel:#172724;--line:#31453e;--text:#e8eee5;--muted:#a6b8ac;--accent:#d8ec9c;--mint:#a8c6ad}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,'PingFang SC','Microsoft YaHei',sans-serif;font-size:16px}button,input,select{font:inherit}button,a,input,select,summary{-webkit-tap-highlight-color:transparent}button,select{cursor:pointer}button{background:#21372f;color:var(--text);border:1px solid #3c5347;border-radius:8px;padding:10px 13px;transition:background .15s}button:hover{background:#345141}button:disabled{opacity:.45;cursor:default}button.active,.primary{background:var(--accent);border-color:var(--accent);color:#1d2c21}a{color:inherit;text-decoration:none}a:hover{text-decoration:underline}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #e0ef9e;outline-offset:3px}header{height:72px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);padding:0 4%;font-size:14px}.brand{font-family:Georgia,serif;font-size:20px}.brand span{font:12px sans-serif;background:#304336;padding:4px 6px;border-radius:4px;margin-left:7px}.header-note{color:var(--muted)}main{max-width:1510px;margin:auto;padding:28px 3%}.title-row{display:flex;justify-content:space-between;align-items:center;margin-bottom:23px}.eyebrow{font-size:12px;letter-spacing:2px;color:var(--mint);line-height:1.6}h1{font-family:Georgia,'Songti SC',serif;font-size:36px;font-weight:500;letter-spacing:3px;margin:8px 0 0}h1 span{font-size:32px;color:var(--accent);margin-left:12px}.stats{font-size:14px;color:var(--muted);text-align:right;line-height:1.7}.modes{display:flex;gap:6px;border-bottom:1px solid var(--line);margin-bottom:24px;padding-bottom:15px}.modes button{border:0;background:transparent;color:var(--muted);padding:12px 22px;font-size:13px}.modes b{margin-left:9px;font-weight:500;font-size:16px}.modes button.active{background:var(--accent);color:#17291c}.workspace{display:grid;grid-template-columns:265px minmax(340px,600px) minmax(260px,1fr);gap:24px;align-items:start}.panel{background:var(--panel);border:1px solid var(--line);border-radius:13px;padding:19px}.section-heading{display:flex;justify-content:space-between;align-items:center;margin-bottom:18px}.section-heading h2{font-size:16px;font-weight:500;margin:0}.section-heading>span{font-size:12px;color:var(--muted)}.library-tabs{display:flex;gap:4px}.library-tabs button{padding:9px 6px;font-size:12px;border:0;flex:1}.search{display:flex;align-items:center;border:1px solid var(--line);background:#101f1a;border-radius:7px;padding:0 10px;margin:16px 0 9px;gap:6px}.search span{font-size:24px;color:var(--muted)}input{width:100%;min-width:0;background:transparent;color:var(--text);border:0;outline:0;font-size:14px;padding:12px 0}input:focus{box-shadow:0 2px var(--accent)}select{width:100%;background:#16271f;color:var(--text);border:1px solid var(--line);border-radius:7px;padding:9px;font-size:14px}.small{color:var(--muted);font-size:13px;line-height:1.7}.course-list{max-height:565px;overflow:auto;margin:12px -8px 0;padding:0 6px;scrollbar-width:thin;scrollbar-color:#465e4e transparent}.course{display:block;width:100%;text-align:left;background:transparent;border:1px solid transparent;padding:13px 10px;margin-bottom:4px}.course strong{display:block;font-size:14px;font-weight:500;line-height:1.5}.course small{display:block;color:var(--muted);font-size:12px;margin-top:5px;line-height:1.5}.course.selected{background:#2b4133;border-color:#627b4e}.course.selected strong{color:var(--accent)}.player{display:flex;align-items:center;gap:10px;min-height:48px;margin-bottom:13px;font-size:14px}.avatar{background:#304638;border:1px solid #58705b;border-radius:9px;display:grid;place-items:center;width:38px;height:38px;font-size:27px}.avatar.you{background:#dbe5c8;color:#243729}.player b{font-weight:500}.player div>span{display:block;color:var(--muted);font-size:12px;margin-top:4px}.player .turn{margin-left:auto;color:var(--accent);font-size:12px}.board{display:grid;grid-template-columns:repeat(8,1fr);width:100%;aspect-ratio:1;border:5px solid #43584a;border-radius:4px;overflow:hidden;box-shadow:0 18px 45px #0003;margin-bottom:18px;touch-action:manipulation}.sq{position:relative;display:grid;place-items:center;width:100%;min-width:0;padding:0;border:0;border-radius:0;aspect-ratio:1;background:#d5ddbb;color:#182b24}.sq.dark{background:#6b8875}.sq:hover{background:#becf9a}.sq.dark:hover{background:#839f7d}.sq.last{background:#c4cb7c}.sq.dark.last{background:#98a761}.sq.selected{background:#e3e78c}.sq.hinted{box-shadow:inset 0 0 0 4px #f5cf67}.sq.check{background:#c96759}.piece{font-size:clamp(30px,4.3vw,59px);line-height:1;font-family:'Arial Unicode MS','Apple Symbols','DejaVu Sans',serif;pointer-events:none;user-select:none}.piece.white{color:#fffef1;text-shadow:0 1px 1px #15251b,1px 0 #15251b,-1px 0 #15251b,0 -1px #15251b}.piece.black{color:#152820;text-shadow:0 1px #d3dec4}.coord{position:absolute;font-size:11px;font-weight:600;color:#314e38;pointer-events:none}.dark .coord{color:#edf1d8}.rank{left:4px;top:3px}.file{right:4px;bottom:2px}.sq.legal:after{content:'';position:absolute;width:23%;height:23%;background:#243e3966;border-radius:50%;pointer-events:none}.sq.legal:has(.piece):after{width:86%;height:86%;background:transparent;border:4px solid #243e3999}.board-tools{display:grid;grid-template-columns:repeat(4,1fr);gap:6px}.board-tools button{font-size:13px;padding:11px 4px}.quiet{background:transparent;border:0;color:var(--muted);font-size:13px;padding:6px;margin-left:auto}.settings{display:flex;gap:12px;margin-top:18px}.settings label{flex:1;font-size:13px;color:var(--muted)}.settings select{display:block;margin-top:7px}.coach .coach-icon{font-size:26px;color:var(--accent)}.course-title{font-family:Georgia,'Songti SC',serif;font-size:25px;line-height:1.5;font-weight:500;margin:9px 0 14px}.progress{height:4px;border-radius:2px;background:#314539;margin-bottom:7px;overflow:hidden}.progress i{display:block;height:100%;width:0;background:var(--accent);transition:width .2s}.message{margin-top:19px;color:var(--accent);font-size:17px;line-height:1.7}.explanation{font-size:15px;line-height:1.85;margin:10px 0 20px;color:#c4d1c6;white-space:pre-line}.explanation .notation{display:block;font:28px Georgia,serif;letter-spacing:1px;color:#edf6d3;margin-bottom:9px}details{border-top:1px solid var(--line);padding:13px 0}summary{cursor:pointer;font-size:14px;color:#dbe6d2}details p{font-size:14px;line-height:1.9;color:var(--muted);margin:12px 0 0}.moves-heading{display:flex;align-items:center;border-top:1px solid var(--line);margin-top:3px;padding-top:12px}h3{font-size:14px;font-weight:500}.moves{max-height:150px;overflow:auto;font-family:ui-monospace,monospace;font-size:14px;line-height:2;word-spacing:8px;color:#bfcec0}.move-row{display:grid;grid-template-columns:30px 1fr 1fr;padding:1px 7px}.move-row:nth-child(odd){background:#21352c}.move-row span:first-child{color:#819b88}#completion{margin:15px 0}#completion button{display:block;width:100%;margin:8px 0}footer{margin:32px 0 10px;padding-top:20px;border-top:1px solid var(--line);display:flex;flex-wrap:wrap;justify-content:space-between;gap:10px;color:var(--muted);font-size:12px;line-height:1.8}footer p{width:100%;margin:0;max-width:900px}footer a{text-decoration:underline}dialog{background:var(--panel);color:var(--text);border:1px solid var(--line);border-radius:14px;max-width:95vw}dialog::backdrop{background:#0009}dialog div{display:flex;gap:8px}[hidden]{display:none!important}#more{width:100%;font-size:13px;margin-top:12px}@media(min-width:1450px){.piece{font-size:61px}}@media(max-width:1150px){.workspace{grid-template-columns:225px minmax(310px,1fr);gap:18px}.coach{grid-column:1/-1;display:block}.course-list{max-height:475px}.piece{font-size:clamp(34px,6vw,65px)}}@media(max-width:700px){header{height:55px;padding:0 18px}.header-note{display:none}main{padding:20px 14px}.title-row{margin-bottom:15px}h1{font-size:29px}.eyebrow{font-size:11px}.stats{font-size:12px}.modes{gap:3px;padding-bottom:12px;margin-bottom:16px}.modes button{padding:11px 8px;flex:1;font-size:10px}.modes b{font-size:14px;margin-left:4px}.workspace{display:flex;flex-direction:column;gap:18px}.board-area{order:0;width:100%}.coach{order:1;width:100%;padding:17px}.library{order:2;width:100%;padding:17px}.course-list{max-height:360px;display:grid;grid-template-columns:1fr 1fr;gap:3px}.course{margin:0}.course strong{font-size:14px}.piece{font-size:clamp(29px,9vw,57px)}.board{border-width:3px}.player{margin-bottom:9px}.board-tools button{font-size:12px}.settings{margin-top:12px}.coord{font-size:10px}.course-title{font-size:23px}.message{margin-top:13px}footer{margin-top:23px}.library-tabs button{font-size:14px}.header-note{display:none}}@media(prefers-reduced-motion:reduce){*{transition:none!important}}

.mobile-coach{display:none}@media(max-width:700px){.modes button span{display:none}.modes b{white-space:nowrap;margin:0}.mobile-coach{display:block;background:#21392e;border-left:3px solid var(--accent);padding:9px 12px;margin-bottom:12px;border-radius:4px}.mobile-coach>div{display:flex;justify-content:space-between;gap:10px;font-size:12px;color:var(--muted)}.mobile-coach a{white-space:nowrap;color:var(--accent)}.mobile-coach p{font-size:14px;line-height:1.65;margin:5px 0 0;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}#library{scroll-margin-top:14px}}