:root{color-scheme:light;--bg:#f7f8f4;--paper:#fff;--ink:#202b26;--muted:#657168;--line:#dce2d9;--green:#246442;--soft:#e8efe4}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.7 -apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button{cursor:pointer;border:1px solid var(--line);background:white;color:var(--ink);border-radius:7px;padding:8px 14px;white-space:nowrap}button:hover{background:var(--soft)}button:disabled{opacity:.35;cursor:default}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #499462;outline-offset:3px}a{color:inherit;text-decoration:none}header{height:83px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;max-width:1360px;margin:auto;padding:0 36px}header>a:last-child{font-size:13px}.brand{display:flex;align-items:center;gap:12px;font-size:22px;font-weight:750}.brand-mark{font-size:34px;color:var(--green)}.brand small{font-size:10px;letter-spacing:2px;font-weight:500;margin-left:12px;color:var(--muted)}main{max-width:1360px;margin:auto;padding:0 36px}.intro{padding:44px 0 30px}.eyebrow{color:var(--green);font-size:12px;letter-spacing:2px;font-weight:600}h1{font-size:clamp(28px,3.3vw,46px);letter-spacing:-1.5px;line-height:1.3;margin:15px 0}p{color:var(--muted)}.intro>p{margin:0}.prerequisite{display:flex;gap:18px;font-size:12px;margin-top:27px}.prerequisite b{color:var(--green);flex-shrink:0}.prerequisite span{color:var(--muted)}.stages{display:grid;grid-template-columns:repeat(3,1fr);border:1px solid var(--line);border-radius:10px;overflow:hidden}.stages button{border:0;border-right:1px solid var(--line);border-radius:0;display:flex;text-align:left;align-items:center;gap:20px;padding:19px 24px;background:transparent}.stages button:last-child{border:0}.stages button>span{font:15px ui-monospace,monospace;color:#849184}.stages b{font-size:23px;letter-spacing:1px}.stages small{display:block;color:var(--muted);font-size:12px}.stages em{font-size:12px;font-style:normal;margin-left:auto;color:var(--muted)}.stages .active{background:var(--soft);box-shadow:inset 0 -3px var(--green)}.stages .active b{color:var(--green)}.lesson-intro{padding:28px 0 20px}.lesson-intro h2{font-size:21px;margin:0}.lesson-intro p{font-size:13px;margin:6px 0 0}.workspace{display:grid;grid-template-columns:245px minmax(0,1fr);border:1px solid var(--line);border-radius:10px;background:white;overflow:hidden}aside{padding:21px 15px;border-right:1px solid var(--line);background:#fafbf8}.library-heading{display:flex;justify-content:space-between;align-items:center;margin:0 6px 15px}h3{font-size:14px;margin:0}.library-heading span{font:12px ui-monospace,monospace;color:var(--muted)}.search>span{position:absolute;clip-path:inset(50%)}input[type=search]{width:100%;border:1px solid var(--line);border-radius:6px;background:white;padding:8px 11px;font-size:12px;color:var(--ink)}.filter-label{display:block;font-size:11px;color:var(--muted);margin:12px 2px}select{color:var(--ink);background:white;border:1px solid var(--line);border-radius:5px;padding:5px;font-size:12px}.filter-label select{display:block;width:100%;margin-top:4px}.case-list{max-height:720px;overflow:auto;scrollbar-width:thin}.case-option{display:flex;align-items:center;gap:12px;width:100%;background:transparent;border:0;text-align:left;border-radius:6px;padding:10px 7px;margin-bottom:3px}.case-option.active{background:var(--soft);color:var(--green)}.case-option b{font:600 13px ui-monospace,monospace}.case-option small{font-size:10px;display:block;color:var(--muted)}.case-option .check{margin-left:auto;font-size:12px}.mini{width:45px;height:40px;flex-shrink:0}.lesson{padding:24px 28px;min-width:0}.lesson-heading{display:flex;justify-content:space-between;align-items:center}.case-category{font-size:11px;color:var(--green)}.lesson-heading h2{font-size:27px;margin:3px 0 18px;line-height:1.4}.quiet{font-size:12px}.quiet.done{background:var(--soft);color:var(--green)}.demo-layout{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(200px,1fr);gap:24px}.visual{background:#f5f7f2;border:1px solid #e7ebe2;border-radius:8px;padding:15px 17px 12px;min-width:0}.view-bar{display:flex;align-items:center;justify-content:space-between;font-size:11px;color:var(--muted)}.text-button{padding:0;border:0;background:transparent;font-size:11px;color:var(--green)}#cube{width:100%;height:auto;display:block;touch-action:none;cursor:grab;aspect-ratio:1.22}#cube:active{cursor:grabbing}.canvas-hint{text-align:center;font-size:10px;margin:0 0 15px;color:#64725f}.controls{display:flex;justify-content:center;gap:6px}.controls button{padding:7px 11px;font-size:12px}.controls .primary{background:var(--green);border-color:var(--green);color:white;min-width:100px}.controls select{height:37px}.position{display:flex;justify-content:space-between;gap:8px;margin-top:15px;font-size:10px;color:var(--muted)}#current-move{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}input[type=range]{accent-color:var(--green);width:100%;height:4px;margin:12px 0}.guidance h3{margin:7px 0}.guidance p{font-size:12px;line-height:1.8;margin:6px 0}.guidance ol{padding-left:18px;font-size:12px;color:var(--muted)}.guidance li{margin:7px 0}.net{display:grid;grid-template-columns:repeat(4,1fr);grid-template-rows:repeat(3,1fr);gap:4px;width:100%;max-width:242px;margin:20px 0 10px}.net-face{position:relative;display:grid;grid-template-columns:repeat(3,1fr);gap:2px;border:3px solid #222b25;background:#222b25;border-radius:4px;aspect-ratio:1}.net-face span{border-radius:2px;display:flex;align-items:center;justify-content:center;font-size:9px;font-weight:800;line-height:1;color:#111}.net .U{grid-area:1/2}.net .L{grid-area:2/1}.net .F{grid-area:2/2}.net .R{grid-area:2/3}.net .B{grid-area:2/4}.net .D{grid-area:3/2}.net-note{font-size:10px!important}.algorithm{margin-top:25px;border-top:1px solid var(--line);padding-top:19px}.algorithm-heading{display:flex;justify-content:space-between;align-items:center}.formula-note{font-size:11px;margin:7px 0 12px}.moves{display:flex;gap:6px;flex-wrap:wrap}.moves button{font:600 19px ui-monospace,monospace;padding:8px 10px;min-width:42px;position:relative}.moves button small{display:block;font:9px ui-monospace,monospace;color:var(--muted);margin-top:6px}.moves .past{background:var(--soft);border-color:#ceddca}.moves .current{background:var(--green);color:white;border-color:var(--green)}.moves .current small{color:#e1ebdc}details{font-size:12px;margin-top:18px}summary{cursor:pointer;color:var(--green)}.steps{columns:2;column-gap:35px;padding-left:25px;color:var(--muted)}.steps li{padding:4px;break-inside:avoid}.sample-note{font-size:10px;margin:18px 0 0;color:#778174}.notation{padding:52px 0;display:grid;grid-template-columns:1fr 1.25fr;gap:65px}.notation h2{font-size:23px;max-width:340px;margin:0}.notation p{font-size:12px}.notation-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px 30px}.notation-grid b{font:600 16px ui-monospace,monospace}.notation-grid p{margin:6px 0}footer{border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:16px;padding:22px 0 30px;font-size:10px;color:var(--muted)}footer a{text-decoration:underline;text-underline-offset:3px}.empty{font-size:12px;padding:20px 8px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}@media(min-width:1450px){.intro{padding-top:50px}#cube{max-height:385px}}@media(max-width:1050px){.workspace{grid-template-columns:205px minmax(0,1fr)}.lesson{padding:20px}.demo-layout{grid-template-columns:1fr}.guidance{display:grid;grid-template-columns:1fr 1fr;column-gap:24px}.guidance .net{grid-column:2;grid-row:1/4;max-width:210px;margin:5px 0}.guidance .net-note{grid-column:2}.guidance ol{grid-column:1}.guidance h3{grid-column:1}.guidance p{grid-column:1}#cube{max-height:340px}.stages button{padding:15px;gap:12px}}@media(max-width:700px){header{height:65px;padding:0 18px}.brand small{display:none}main{padding:0 16px}.intro{padding-top:30px}.intro>p{font-size:13px}.prerequisite{display:block}.prerequisite b{display:block;margin-bottom:5px}.stages button{padding:12px 9px;gap:6px}.stages button>span,.stages em{display:none}.stages b{font-size:19px}.stages small{font-size:10px}.workspace{display:block}aside{border-right:0;border-bottom:1px solid var(--line);padding:15px}.library-heading{margin-bottom:8px}.filter-label{margin:8px 0}.case-list{max-height:160px;display:grid;grid-template-columns:1fr 1fr;gap:2px}.case-option{padding:6px}.lesson{padding:17px 14px}.lesson-heading h2{font-size:23px}.demo-layout{gap:18px}.visual{padding:12px}.controls{gap:5px}.controls button{padding:7px 10px}.position{font-size:9px}.guidance{column-gap:12px}.guidance p,.guidance ol{font-size:11px}.steps{columns:1}.notation{display:block;padding:35px 0}.notation-grid{margin-top:22px;gap:18px}.notation h2{font-size:22px}footer{display:block}footer>div{margin-top:8px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}
/* Scramble practice sits after the three CFOP learning stages. */
.stages{grid-template-columns:repeat(4,minmax(0,1fr))}.stages button{gap:12px;padding:18px 16px}.stages em{flex-shrink:0}@media(max-width:1050px){.stages button>span{display:none}.stages button{padding:15px 12px}.stages em{font-size:10px}}@media(max-width:700px){.stages{grid-template-columns:repeat(2,minmax(0,1fr))}.stages button{padding:12px 14px}.stages button:nth-child(-n+2){border-bottom:1px solid var(--line)}.stages button:nth-child(2){border-right:0}.stages em{display:block}}
[hidden]{display:none!important}.stages{grid-template-columns:repeat(5,minmax(0,1fr))}.stages button>span{display:none}.stages b{font-size:21px}.stages button{padding:16px 12px;gap:8px}.chain-panel{padding:16px 18px;background:var(--soft);border-radius:8px;margin:0 0 22px}.chain-panel p{font-size:12px;margin:6px 0}.chain-panel .chain-order{font:600 14px/2 ui-monospace,monospace;color:var(--green)}.chain-current{display:grid;gap:4px;font-size:12px;margin:15px 0}.chain-current b{font-size:15px}.chain-current span{color:var(--muted)}.chain-timer{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:16px}.chain-timer output{font:600 25px ui-monospace,monospace;min-width:135px;font-variant-numeric:tabular-nums}.chain-timer button,.chain-timer label{font-size:12px}.chain-timer input{accent-color:var(--green)}.chain-panel .timer-help{font-size:10px;margin-top:10px}.chain-index{font:12px ui-monospace,monospace;color:var(--muted);padding:6px}.chain-moves{max-height:240px;overflow:auto;padding:4px;align-content:start}.chain-formula-row{padding:12px 0;border-bottom:1px solid var(--line)}.chain-formula-row h4{margin:0 0 5px}.chain-formula-row code{font:13px/1.9 ui-monospace,monospace;overflow-wrap:anywhere}.chain-formula-row p{font-size:11px;margin:5px 0}@media(max-width:1050px){.stages em{display:none}.stages b{font-size:19px}}@media(max-width:700px){.stages{grid-template-columns:repeat(2,minmax(0,1fr))}.stages button:nth-child(-n+4){border-bottom:1px solid var(--line)}.stages button:nth-child(4){border-right:0}.stages button:last-child{grid-column:1/-1}.stages em{display:block}.chain-timer{gap:8px}.chain-timer output{min-width:115px}.chain-panel{padding:12px}}