:root{--bg:#14161a;--panel:#1b1e24;--line:#2b3038;--text:#d7dce3;--dim:#838d9b;--accent:#7cc4ff;--good:#6cd08a;--bad:#f08a7a;--kw:#c792ea;--num:#d7a87a;--comment:#5c6673;--mono:ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;--lightningcss-light: ;--lightningcss-dark:initial;color-scheme:dark}*{box-sizing:border-box;border-radius:0}body{background:var(--bg);color:var(--text);font:14px/1.65 var(--mono);margin:0}#app{flex-direction:column;min-height:100vh;display:flex}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}nav{border-bottom:1px solid var(--line);align-items:center;gap:20px;padding:7px 16px;font-size:12px;display:flex}nav .spacer{flex:1}.course{width:100%;max-width:640px;margin:0;padding:20px 24px 80px}.course h1{letter-spacing:-.01em;margin:0 0 16px;font-size:22px;font-weight:600}.course section{margin-bottom:44px}.course header{align-items:baseline;gap:12px;display:flex}.course h2{margin:0;font-size:14px;font-weight:600}.course .count{color:var(--dim);font-variant-numeric:tabular-nums;margin-left:auto;font-size:12px}.course .desc{color:var(--dim);margin:4px 0 16px;font-size:12px}.course ol{border-top:1px solid var(--line);margin:0;padding:0;list-style:none}.course li{border-bottom:1px solid var(--line);font-size:13px}.course li a{color:var(--text);align-items:baseline;gap:14px;padding:9px 10px;display:flex}.course li a:hover{background:var(--panel);text-decoration:none}.course li .n{color:var(--dim);font-variant-numeric:tabular-nums}.course li .t{flex:1}.course li .kind{color:var(--dim);font-size:11px}.course li .count{font-size:12px}.course li .mark{text-align:right;width:2ch;color:var(--dim);font-weight:600}.course li.done .mark{color:var(--good)}.course li.done .t{color:var(--dim)}.course li.empty{color:var(--dim);padding:9px 10px}nav .dim{color:var(--dim)}.menu{position:relative}.menu-btn{color:var(--dim);font:14px var(--mono);cursor:pointer;background:0 0;border:0;padding:0 2px}.menu-btn:hover,.menu-btn[aria-expanded=true]{color:var(--text)}.menu-pop{z-index:10;background:var(--panel);border:1px solid var(--line);min-width:260px;padding:6px 0 8px;font-size:12px;position:absolute;top:calc(100% + 8px);right:0}.menu-h{color:var(--dim);letter-spacing:.06em;text-transform:uppercase;padding:4px 12px 6px;font-size:11px}.menu-pop ul{margin:0;padding:0;list-style:none}.menu-pop li{grid-template-columns:1fr auto auto;align-items:center;gap:6px;padding:3px 12px;display:grid}.menu-pop li .name{color:var(--text)}.menu-pop li button{color:var(--dim);font:11px var(--mono);cursor:pointer;background:0 0;border:1px solid #0000;align-items:center;gap:6px;padding:2px 7px;display:flex}.menu-pop li button i{background:var(--sw);border:1px solid var(--line);width:12px;height:12px;box-shadow:inset 4px 0 0 var(--sa)}.menu-pop li button:hover{color:var(--text);border-color:var(--line)}.menu-pop li button.on{color:var(--text);border-color:var(--accent)}.lesson{--rail-w:30%;grid-template-columns:minmax(0, 1fr) 6px minmax(220px, var(--rail-w));flex:1;min-height:0;display:grid}.gutter{background:var(--line);-webkit-user-select:none;user-select:none;touch-action:none;flex:none;transition:background .1s}.gutter:hover,.gutter.active{background:var(--accent)}.gutter-v{cursor:col-resize;width:6px}.gutter-h{cursor:row-resize;height:6px}.reading{width:100%;max-width:680px;margin:0 auto;padding:40px 20px 80px}.rail{background:color-mix(in srgb, var(--panel) 50%, var(--bg));border-left:0;overflow-y:auto}.rail .prose{padding:24px 22px 60px}.rail .prose p,.rail .prose ul,.rail .prose ol,.rail .prose pre{max-width:none}.prose{padding:32px 28px 60px}.prose h1{margin:0 0 20px;font-size:18px;font-weight:600}.prose p,.prose ul,.prose ol{max-width:56ch}.prose code{background:var(--panel);padding:1px 4px}.prose pre{background:var(--panel);border:1px solid var(--line);padding:12px 14px;font-size:13px;overflow-x:auto}.prose pre code{background:0 0;padding:0}.workspace{flex-direction:column;min-height:0;display:flex}#editor{flex:none;height:44vh;overflow:hidden}#editor .cm-editor{height:100%}.bar{border-bottom:1px solid var(--line);flex-wrap:wrap;align-items:center;gap:12px;padding:6px 12px;font-size:12px;display:flex}.run{background:var(--accent);color:var(--bg);font:600 12px var(--mono);cursor:pointer;border:0;padding:4px 14px}.run:disabled{opacity:.5;cursor:default}.bar .hint{color:var(--dim)}.bar .task{flex:1;min-width:16ch}.bar .task code{background:var(--panel);padding:1px 4px}#status{color:var(--dim);white-space:nowrap;margin-left:auto}.results{flex-direction:column;flex:1;min-height:0;display:flex}.checks{border-bottom:1px solid var(--line);margin:0;padding:8px 14px;font-size:13px;list-style:none}.checks:empty{display:none}.checks li{gap:10px;padding:2px 0;display:flex}.checks .mark{flex:none;width:2ch;font-weight:600}.checks .ok .mark{color:var(--good)}.checks .fail .mark{color:var(--bad)}.checks .skip,.checks .hint{color:var(--dim)}.checks .hint:before{content:"— "}.output{white-space:pre-wrap;min-height:0;font:13px/1.5 var(--mono);color:var(--dim);flex:1;margin:0;padding:10px 14px;overflow:auto}.output.good{color:var(--good)}.output.bad{color:var(--bad)}.prose h2{margin-top:32px;font-size:14px;font-weight:600}.prose h2:last-of-type{color:var(--dim)}.prose h2:last-of-type+ul{margin:8px 0 0;padding-left:18px;font-size:12px}.prose h2:last-of-type+ul li{color:var(--dim)}@media (width<=900px){.lesson{grid-template-columns:1fr}.gutter-v{display:none}.workspace{min-height:60vh}.rail{border-left:0;border-top:1px solid var(--line)}}