:root{color-scheme:light;--bg:oklch(1 0 0);--surface:oklch(.97 0 0);--ink:oklch(.25 .012 60);--muted:oklch(.46 .015 60);--primary:oklch(.49 .12 60);--tint:oklch(.95 .035 60);--line:oklch(.86 .005 60);--accent:oklch(.36 .065 230);--success:oklch(.4 .07 160);--danger:oklch(.46 .15 25);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;font-size:16px;line-height:1.65}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);min-width:320px}a{color:var(--primary);text-underline-offset:4px}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:not-allowed;opacity:.5}button:active:not(:disabled){transform:translateY(1px)}:focus-visible{outline:3px solid var(--primary);outline-offset:4px}h1,h2,h3{line-height:1.35;text-wrap:balance;letter-spacing:-.025em}p{max-width:72ch;text-wrap:pretty}h2{font-size:1.15rem}h3{font-size:1.05rem}code,pre{font-family:ui-monospace,SFMono-Regular,Consolas,monospace}button{transition:background 160ms ease-out,color 160ms ease-out}button:hover:not(:disabled){background:var(--tint)}[hidden]{display:none!important}.skip{position:fixed;top:-80px;left:16px;background:var(--ink);color:white;padding:12px;z-index:3}.skip:focus{top:12px}
.header{height:88px;padding-inline:40px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:flex;align-items:center;gap:12px;color:var(--ink);font-weight:750;text-decoration:none;font-size:1.1rem}.brand-symbol{width:44px;height:44px;background:var(--primary);color:var(--bg);border-radius:10px;display:grid;place-items:center;font-weight:800;font-size:1.3rem}.brand small{display:block;color:var(--muted);font-size:.75rem;font-weight:500}.header nav{display:flex;gap:28px;font-size:.9rem}.header nav a{color:var(--muted);text-decoration:none}
.workspace{display:grid;grid-template-columns:260px minmax(0,1fr);max-width:1600px;margin:auto}.curriculum{border-right:1px solid var(--line);padding:32px 20px;background:var(--surface)}.sidebar-heading{padding-inline:12px;margin-bottom:24px}.sidebar-heading h2{margin:0 0 4px}.sidebar-heading span{color:var(--muted);font-size:.8rem}.course-item{display:flex;width:100%;align-items:center;gap:12px;padding:12px;border:0;background:transparent;color:var(--ink);text-align:left;border-radius:8px;margin-bottom:4px;text-decoration:none}.course-item .course-number{font-family:ui-monospace,monospace;font-size:.8rem;color:var(--muted);min-width:23px}.course-item strong{display:block;font-size:.9rem;font-weight:650}.course-item small{display:block;color:var(--muted);font-size:.7rem}.course-item[aria-current="step"]{background:var(--tint);color:var(--primary)}.course-item:hover{background:var(--tint)}.course-done{margin-left:auto;color:var(--success)}.progress-box{padding:24px 12px 0;border-top:1px solid var(--line);margin-top:28px;font-size:.75rem}.progress-box label{display:flex;justify-content:space-between;gap:8px}.progress-box progress{accent-color:var(--primary);width:100%;height:6px;display:block;margin-top:12px}.progress-box p{color:var(--muted);font-size:.7rem}.branch-link{display:block;margin:26px 12px;font-size:.8rem}.text-button{padding:5px 0;min-height:36px;border:0;background:transparent;color:var(--primary);text-decoration:underline;text-underline-offset:4px;font-size:.8rem}
main{min-width:0;padding:44px clamp(24px,4vw,64px) 0}.lesson-topline{display:flex;justify-content:space-between;gap:12px;font-size:.8rem;color:var(--primary)}.reading-tag{color:var(--muted)}h1{font-size:2.35rem;margin:18px 0 12px}.lead{font-size:1rem;color:var(--muted);margin-top:0}.lesson-actions{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:24px}.button{display:inline-flex;justify-content:center;align-items:center;min-height:42px;padding:8px 16px;border:1px solid var(--line);border-radius:7px;background:var(--bg);color:var(--ink);font-size:.85rem;font-weight:600;text-decoration:none}.button:hover{background:var(--tint)}.primary{background:var(--primary);border-color:var(--primary);color:var(--bg)}.primary:hover:not(:disabled){background:var(--ink);color:var(--bg)}.completion{display:flex;align-items:center;gap:6px;color:var(--muted);font-size:.78rem;margin-left:auto;min-height:44px}.completion input{width:17px;height:17px;accent-color:var(--primary)}.lesson-notes{display:grid;grid-template-columns:1fr 1fr;gap:40px;border-top:1px solid var(--line);margin-top:32px;padding:20px 0 28px}.lesson-notes h2{font-size:.85rem;margin:0 0 6px}.lesson-notes p{font-size:.8rem;color:var(--muted);margin:0}
.labs{scroll-margin-top:20px}.section-title{display:flex;align-items:baseline;justify-content:space-between;gap:15px;margin-bottom:16px}.section-title h2{margin:0;font-size:1.2rem}.section-title span{font-size:.7rem;color:var(--muted)}.lab-tabs{display:flex;border-bottom:1px solid var(--line);gap:24px}.lab-tabs button{min-height:48px;padding:12px 0;border:0;border-bottom:2px solid transparent;background:transparent;color:var(--muted);font-size:.85rem}.lab-tabs button[aria-selected="true"]{color:var(--primary);border-bottom-color:var(--primary);font-weight:700}.lab-toolbar{display:flex;flex-wrap:wrap;align-items:center;gap:16px;padding:18px 0;font-size:.75rem}.lab-toolbar label{display:flex;align-items:center;gap:8px}.lab-toolbar select{max-width:100%;font-size:.75rem;color:var(--ink);padding:8px 26px 8px 10px;border:1px solid var(--line);border-radius:6px;background:var(--bg);min-height:40px}.lab-toolbar>span{color:var(--muted)}.lab-toolbar>.text-button{margin-left:auto}
.channel-stage{display:grid;grid-template-columns:1fr 1.3fr 1fr;gap:16px;background:var(--surface);border-radius:12px;padding:28px 22px;min-height:245px;align-items:center}.actor{text-align:center;min-width:0}.actor-type{color:var(--muted);font-size:.7rem;font-family:ui-monospace,monospace}.actor h3{margin:6px 0 12px}.actor-value{font-size:.85rem;min-height:28px}.state{display:block;font-size:.72rem;color:var(--success);margin:4px 0 18px}.state.waiting{color:var(--primary)}.actor .button{font-size:.75rem;padding:8px 10px;width:100%}.channel-middle{position:relative;text-align:center;min-width:0}.buffer-label{font-size:.65rem;color:var(--muted);overflow-wrap:anywhere}.buffer{display:flex;justify-content:center;gap:7px;margin:20px 0 12px;min-height:46px}.slot{display:grid;place-items:center;width:40px;height:44px;border:1px dashed var(--line);border-radius:6px;color:var(--muted);font:700 1rem ui-monospace,monospace;background:var(--bg)}.slot.filled{background:var(--primary);color:var(--bg);border-color:var(--primary);animation:arrive 220ms ease-out}.handoff{display:flex;align-items:center;justify-content:center;border:1px dashed var(--line);border-radius:7px;padding:8px;font-size:.72rem;color:var(--muted);width:100%}#buffer-count{font-size:.7rem;color:var(--muted)}.connection-arrow{position:absolute;top:45%;font-size:1.3rem;color:var(--primary)}.connection-arrow:first-child{left:-15px}.connection-arrow:last-child{right:-15px}.lab-message{padding:14px 18px;background:var(--tint);color:var(--ink);border-radius:7px;font-size:.82rem;margin:16px 0;max-width:none;min-height:55px}.lab-footer{display:flex;align-items:center;gap:18px}.lab-footer span{color:var(--muted);font-size:.7rem}.explanation{margin-top:18px;border-top:1px solid var(--line);padding-top:16px;font-size:.8rem}.explanation summary{cursor:pointer;min-height:32px;font-weight:600}.explanation p{color:var(--muted)}
.gateway-stage{display:flex;align-items:center;gap:12px;background:var(--surface);padding:26px 20px;border-radius:12px;min-height:245px}.route-node{flex:1;padding:16px 12px;border:1px solid var(--line);border-radius:8px;background:var(--bg);min-width:0;transition:background 200ms ease-out,border-color 200ms ease-out}.route-node h3{margin:6px 0}.route-node small,.route-node span{font-size:.65rem;color:var(--muted);display:block;overflow-wrap:anywhere}.route-node.active{background:var(--tint);border-color:var(--primary)}.route-node.failed{border-color:var(--danger);background:oklch(.97 .015 25)}.route-arrow{color:var(--primary)}.upstreams{flex:1;display:flex;flex-direction:column;gap:8px}.upstreams .route-node{padding:8px 12px}.playback{display:flex;align-items:center;flex-wrap:wrap;gap:12px;margin-top:18px}.playback>span{margin-left:auto;font: .8rem ui-monospace,monospace;color:var(--muted)}.stream-output{display:grid;grid-template-columns:1fr 1fr;gap:28px;padding:8px 0}.stream-output h3{font-size:.8rem;margin:0 0 12px}.stream-output p{min-height:44px;margin:0 0 6px;font-size:1.1rem}.stream-output span{font-size:.7rem;color:var(--muted)}#trace{font: .7rem/1.8 ui-monospace,monospace;margin:0;padding-left:22px;min-height:126px;color:var(--muted)}
.practice{display:grid;grid-template-columns:1fr 1.15fr;gap:30px;margin-top:40px;padding-block:30px;border-top:1px solid var(--line)}.practice h2{margin-top:0}.practice p,.practice a{font-size:.8rem;color:var(--muted)}.command-panel{min-width:0;border-radius:8px;background:var(--surface);padding:16px}.command-panel>div{display:flex;align-items:center;justify-content:space-between;gap:8px;font-size:.7rem;color:var(--muted)}pre{margin:12px 0;font-size:.73rem;white-space:pre-wrap;overflow-wrap:anywhere}.command-panel p{margin:0}footer{display:flex;justify-content:space-between;gap:16px;padding-block:24px;border-top:1px solid var(--line);font-size:.7rem;color:var(--muted)}footer a{color:var(--muted)}noscript{padding:16px;display:block}@keyframes arrive{from{transform:translateY(-8px);opacity:.4}to{transform:translateY(0);opacity:1}}
@media(min-width:1300px){.curriculum{padding-inline:24px}.workspace{grid-template-columns:280px minmax(0,1fr)}}
@media(max-width:1050px){.workspace{grid-template-columns:220px minmax(0,1fr)}main{padding-inline:24px}.completion{margin-left:0}.channel-stage{gap:12px;padding:22px 12px}.reading-tag{display:none}.section-title{display:block}.section-title span{display:block;margin-top:6px}.practice{grid-template-columns:1fr}.gateway-stage{gap:6px;padding:22px 10px}}
@media(max-width:760px){.header{height:76px;padding-inline:18px}.header nav{gap:16px;font-size:.75rem}.workspace{display:block}.curriculum{border-right:0;border-bottom:1px solid var(--line);padding:18px}.sidebar-heading{display:none}#course-list{display:flex;overflow-x:auto;gap:6px;padding-bottom:8px}.course-item{min-width:150px;margin:0}.progress-box{margin:10px 0 0;padding:0;border:0}.progress-box p,.progress-box .text-button,.branch-link{display:none}.progress-box label{font-size:.7rem}.progress-box progress{margin-top:6px}main{padding:28px 18px 0}h1{font-size:1.85rem}.lesson-notes{gap:20px}.lab-toolbar>span{display:none}.lab-tabs{gap:16px}.lab-tabs button{font-size:.78rem}.channel-stage{grid-template-columns:1fr 1.05fr 1fr;padding:22px 10px;gap:12px}.buffer{gap:3px}.slot{width:28px;height:36px;font-size:.8rem}.actor h3{font-size:.95rem}.actor-value{font-size:.7rem}.actor .button{font-size:.68rem;padding:8px 4px}.actor-type{font-size:.6rem}.buffer-label{font-size:.57rem}.connection-arrow{display:none}.lab-footer{align-items:flex-start;gap:16px}.lab-footer button{white-space:nowrap}.stream-output{gap:18px}.route-node{padding:10px 7px}.route-node h3{font-size:.88rem}.route-node span{font-size:.58rem}.gateway-stage{gap:5px}footer{flex-wrap:wrap}.lesson-actions .button{font-size:.78rem}.completion{font-size:.73rem}.lab-toolbar label{flex-wrap:wrap}}
@media(max-width:380px){.header nav a:first-child{display:none}.lesson-notes{grid-template-columns:1fr;gap:16px}.channel-stage{gap:7px;padding-inline:7px}.slot{width:21px}.stream-output{grid-template-columns:1fr}.route-arrow{display:none}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important}html{scroll-behavior:auto}}
.course-lab-title{font-size:1rem;margin:0;padding:12px 0;border-bottom:2px solid var(--primary);color:var(--primary)}
.course-diagram{display:flex;gap:14px;align-items:stretch;background:var(--surface);border-radius:12px;padding:26px 18px;min-height:180px}
.concept-node{position:relative;flex:1;min-width:0;display:flex;flex-direction:column;justify-content:center;gap:10px;padding:16px 12px;border:1px solid var(--line);border-radius:8px;background:var(--bg);transition:background 180ms ease-out,border-color 180ms ease-out}
.concept-node:not(:last-child)::after{content:'→';position:absolute;right:-14px;color:var(--primary)}
.concept-node.current{border-color:var(--primary);background:var(--tint)}
.concept-node.failed{border-color:var(--danger)}
.concept-node strong{font-size:.82rem;overflow-wrap:anywhere}.concept-number{font:.7rem ui-monospace,monospace;color:var(--muted)}.concept-marker{font-size:.65rem;color:var(--primary)}
.course-details{display:grid;grid-template-columns:1.2fr 1fr;gap:24px;padding:16px 0}.course-details>div{min-width:0}.course-details h3{font-size:.8rem;margin:0 0 12px}.course-details pre{padding:16px;background:var(--surface);border-radius:8px;min-height:90px;margin:0}.course-values{margin:0;font-size:.8rem}.course-values>div{display:flex;justify-content:space-between;gap:16px;padding:6px 0;border-bottom:1px solid var(--line)}.course-values dt{color:var(--muted)}.course-values dd{margin:0;overflow-wrap:anywhere;text-align:right}.value-empty{color:var(--muted)}.course-trace{padding-left:22px;color:var(--muted)}
@media(max-width:760px){.course-diagram{flex-direction:column;gap:18px;padding:18px}.concept-node{padding:12px;flex-direction:row;justify-content:flex-start;align-items:center;gap:12px;min-height:54px}.concept-node:not(:last-child)::after{content:'↓';right:50%;bottom:-21px}.concept-marker{margin-left:auto}.course-details{grid-template-columns:1fr}.playback .button{font-size:.75rem;padding:8px 12px}}