/* C 语言实验室 · shared static site design */
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
:root{color-scheme:dark;--bg:#21222c;--surface:#282a36;--panel:#30323f;--line:#3d4051;--fg:#f8f8f2;--muted:#b5b7cc;--accent:#bd93f9;--cyan:#8be9fd;--green:#50fa7b;--pink:#ff79c6;--yellow:#f1fa8c;--mono:ui-monospace,SFMono-Regular,Consolas,"Liberation Mono",monospace;--sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:110px}body{margin:0;background:var(--bg);color:var(--fg);font:14px/1.7 var(--sans);-webkit-font-smoothing:antialiased}a{color:inherit;text-decoration:none}button,input,select{font:inherit}button{cursor:pointer;color:inherit}button,a,input,select{-webkit-tap-highlight-color:transparent}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:2px solid var(--accent);outline-offset:5px}button{border:0}::selection{background:#bd93f94a;color:var(--fg)}svg{vertical-align:middle}code,pre,kbd{font-family:var(--mono)}[hidden]{display:none!important}.container{width:min(1216px,calc(100% - 96px));margin-inline:auto}.skip-link{position:fixed;top:-80px;left:20px;z-index:50;background:var(--accent);color:var(--bg);padding:10px 20px;border-radius:6px}.skip-link:focus{top:12px}.site-header{height:88px;border-bottom:1px solid var(--line);position:relative;z-index:20;background:var(--bg)}.header-inner{display:flex;align-items:center;justify-content:space-between;height:100%;gap:30px}.site-brand{display:inline-flex;align-items:center;gap:11px;flex-shrink:0}.brand-mark{width:38px;height:38px;display:grid;place-items:center;background:var(--accent);color:#21222c;border-radius:9px;font:700 23px var(--mono);letter-spacing:-3px;padding-right:3px}.site-brand-text{display:grid;gap:1px}.site-brand-text strong{font-size:16px;letter-spacing:1px;font-weight:650}.site-brand-text small{font:9px var(--mono);color:var(--muted);letter-spacing:2.4px}.site-nav{display:flex;align-items:center;gap:30px;margin-right:auto;margin-left:52px;height:100%}.site-nav a{height:100%;display:flex;align-items:center;position:relative;color:var(--muted);font-size:13px}.site-nav a:hover,.site-nav a[aria-current=page]{color:var(--fg)}.site-nav a[aria-current=page]::after{content:"";position:absolute;bottom:-1px;left:0;right:0;height:2px;background:var(--accent)}.header-actions{display:flex;align-items:center;gap:22px}.nav-progress{font:11px var(--mono);color:var(--muted);display:flex;align-items:center;gap:8px}.status-dot{display:inline-block;width:6px;height:6px;border-radius:50%;background:var(--green);box-shadow:0 0 0 4px #50fa7b0b}.button{display:inline-flex;justify-content:center;align-items:center;gap:20px;padding:13px 21px;border:1px solid var(--line);border-radius:7px;background:transparent;color:var(--fg);font-size:13px;font-weight:500;line-height:1.5;transition:background .2s,border-color .2s,transform .2s}.button:hover{border-color:var(--accent);background:#bd93f90b;transform:translateY(-2px)}.button-primary{background:var(--accent);color:#21222c;border-color:var(--accent);font-weight:650}.button-primary:hover{background:#cdaffa}.button-small{padding:10px 14px;font-size:12px;gap:18px}.arrow{font-family:var(--mono);font-size:19px;line-height:1}.menu-toggle{display:none;background:transparent;border:1px solid var(--line);border-radius:5px;width:39px;height:39px;font-size:20px}.eyebrow-label{font:10px/1.7 var(--mono);letter-spacing:2px;text-transform:uppercase;color:var(--accent);display:flex;align-items:center;gap:10px}.eyebrow-label::before{content:"";width:19px;height:1px;background:currentColor}.subtle{color:var(--muted)}.mono{font-family:var(--mono)}
.hero{padding:86px 0 64px;display:grid;grid-template-columns:1fr 1fr;gap:62px;align-items:center}.hero-copy h1{font-size:clamp(43px,4.1vw,62px);font-weight:650;letter-spacing:-2.5px;line-height:1.34;margin:24px 0 24px}.hero-copy h1 em{font-style:normal;color:var(--accent);position:relative;white-space:nowrap}.hero-copy h1 em::after{content:"";position:absolute;left:1px;right:0;bottom:-8px;height:7px;border-top:2px solid var(--accent);border-radius:50%;transform:rotate(-2deg);opacity:.55}.hero-copy>p{color:var(--muted);font-size:14px;line-height:1.95;max-width:420px;margin:0}.hero-actions{display:flex;gap:14px;margin:32px 0 22px}.hero-footnote{display:flex;align-items:center;gap:17px;font-size:10px;color:var(--muted)}.hero-footnote span{display:flex;align-items:center;gap:6px}.hero-footnote b{font-weight:400;color:var(--green)}.demo-wrap{position:relative;padding:12px 0 45px}.demo-wrap::before{content:"";position:absolute;inset:-24px -22px 0;background-image:radial-gradient(#bd93f935 .8px,transparent .8px);background-size:17px 17px;z-index:-1;mask-image:linear-gradient(transparent,#000 20%,#000 80%,transparent)}.demo-caption{display:flex;justify-content:space-between;align-items:center;margin-bottom:13px;font:10px var(--mono);letter-spacing:1px;color:var(--muted)}.demo-caption span:last-child{color:var(--green);display:flex;align-items:center;gap:8px}.demo-window{border:1px solid #515269;border-radius:11px;background:var(--surface);box-shadow:0 24px 70px #12131b40;overflow:hidden}.window-bar{display:flex;align-items:center;gap:6px;height:45px;background:#30323f;border-bottom:1px solid var(--line);padding:0 17px}.window-dot{width:7px;height:7px;border-radius:50%;background:#ff797b}.window-dot:nth-child(2){background:#f1fa8c}.window-dot:nth-child(3){background:#50fa7b}.window-file{font:10px var(--mono);color:var(--muted);margin-left:13px}.window-label{font:9px var(--mono);color:#8f92aa;margin-left:auto}.demo-source{padding:23px 0 20px}.demo-line{display:flex;align-items:center;min-height:36px;font:12px/1.8 var(--mono);padding:0 19px 0 0;border-left:2px solid transparent;white-space:pre}.demo-line.active{background:#bd93f916;border-left-color:var(--accent)}.demo-ln{color:#858ba8;width:41px;text-align:right;margin-right:20px;font-size:10px;flex-shrink:0}.syntax-type{color:var(--cyan)}.syntax-num{color:var(--accent)}.syntax-key{color:var(--pink)}.syntax-call{color:var(--green)}.syntax-string{color:var(--yellow)}.demo-state{border-top:1px solid var(--line);padding:17px 20px 19px}.demo-state-head{display:flex;justify-content:space-between;font-size:10px;color:var(--muted);margin-bottom:12px}.demo-state-head span:last-child{font-family:var(--mono)}.demo-values{display:grid;grid-template-columns:repeat(3,1fr);gap:9px}.demo-value{border:1px solid var(--line);border-radius:6px;background:var(--bg);padding:10px 12px;transition:border-color .2s}.demo-value.highlight{border-color:var(--accent)}.demo-value small{font:10px var(--mono);color:var(--muted);display:block}.demo-value output{font:23px var(--mono);display:block;margin-top:8px}.demo-value.highlight output{color:var(--accent)}.demo-toolbar{display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--line);padding:12px 16px;gap:10px}.demo-toolbar p{font-size:10px;color:var(--muted);margin:0}.demo-step{padding:8px 13px;border-radius:5px;background:var(--accent);color:var(--bg);font-size:11px;white-space:nowrap}.demo-note{position:absolute;right:12px;bottom:0;display:flex;align-items:center;gap:10px;background:#35313f;border:1px solid #625176;border-radius:6px;padding:9px 14px;font-size:10px;color:#d6c4ed;transform:rotate(-3deg)}.demo-note span{color:var(--accent);font-size:16px}.stats-strip{display:grid;grid-template-columns:repeat(3,1fr);border-block:1px solid var(--line);padding:24px 0;gap:35px}.stat{display:flex;align-items:center;gap:18px;padding-left:35px;border-left:1px solid var(--line)}.stat:first-child{border:0;padding-left:0}.stat strong{font:30px var(--mono);letter-spacing:-1px}.stat span{font-size:11px;color:var(--muted)}.stat small{display:block;font:9px var(--mono);color:#8e92ab;letter-spacing:1px;margin-top:3px}.section{padding:75px 0}.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:25px;margin-bottom:30px}.section-head h2{font-size:29px;letter-spacing:-.7px;margin:10px 0 0;font-weight:550}.section-head>p{color:var(--muted);font-size:12px;margin:0}.text-link{display:inline-flex;gap:15px;align-items:center;font-size:12px;color:var(--muted)}.text-link:hover{color:var(--accent)}.course-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}.course-card{display:flex;flex-direction:column;border:1px solid var(--line);border-radius:9px;background:var(--surface);overflow:hidden;transition:transform .2s,border-color .2s}.course-card:hover{border-color:#83709d;transform:translateY(-5px)}.course-art{height:164px;display:flex;flex-direction:column;justify-content:center;align-items:center;position:relative;background:linear-gradient(145deg,#30313f,#292b37);border-bottom:1px solid var(--line);overflow:hidden}.course-art::after{content:"";position:absolute;inset:0;background-image:linear-gradient(#ffffff04 1px,transparent 1px),linear-gradient(90deg,#ffffff04 1px,transparent 1px);background-size:23px 23px;pointer-events:none}.art-overline{font:9px var(--mono);letter-spacing:1.5px;color:#8d91aa;position:absolute;top:15px;left:18px}.variable-art{display:flex;gap:11px;align-items:center;color:var(--accent);font:18px var(--mono)}.art-box{width:64px;height:65px;border:1px solid #716085;border-radius:6px;display:flex;flex-direction:column;align-items:center;justify-content:center;background:#bd93f908}.art-box small{font:9px var(--mono);color:var(--muted);margin-bottom:6px}.art-box b{font:23px var(--mono)}.art-box.result{background:#bd93f91a;border-color:var(--accent)}.terminal-art{width:78%;border:1px solid #4d5362;border-radius:6px;padding:12px 15px;background:#21222c;font:11px/2 var(--mono)}.terminal-art>small{color:var(--muted);font-size:9px;display:block}.terminal-art .prompt{color:var(--green)}.terminal-art .cursor{display:inline-block;background:var(--green);width:6px;height:12px;vertical-align:middle}.loop-art{display:flex;align-items:center;gap:11px;font:10px var(--mono);position:relative;padding:20px 0}.loop-art::after{content:"↶";position:absolute;left:0;right:0;bottom:-20px;text-align:center;color:var(--cyan);font-size:42px;line-height:1}.loop-art b{display:grid;place-items:center;padding:9px 11px;border:1px solid #627788;border-radius:5px;color:var(--cyan);font-weight:400;background:#8be9fd08}.loop-art span{color:#8693a5}.course-body{padding:23px 23px 19px;display:flex;flex-direction:column;flex:1}.course-meta{display:flex;align-items:center;justify-content:space-between;font:10px var(--mono);color:var(--muted)}.course-meta>span:first-child{color:var(--accent)}.course-body h3{font-size:22px;font-weight:550;margin:13px 0 5px;letter-spacing:-.5px}.course-body p{font-size:12px;line-height:1.85;color:var(--muted);margin:0 0 17px}.course-tags{display:flex;gap:7px;flex-wrap:wrap;margin-bottom:24px}.course-tags span{font:9px var(--mono);background:#ffffff04;border:1px solid var(--line);border-radius:4px;color:var(--muted);padding:2px 7px}.course-card-bottom{display:flex;justify-content:space-between;align-items:center;border-top:1px solid var(--line);padding-top:15px;margin-top:auto;font-size:11px}.course-status{color:#b5b7cc;font-size:10px}.course-status.done{color:var(--green)}.course-card-bottom .arrow{color:var(--accent)}.method-section{border-top:1px solid var(--line);padding-bottom:80px}.method-layout{display:grid;grid-template-columns:.9fr 1.8fr;gap:70px;align-items:start}.method-heading h2{font-size:30px;font-weight:550;line-height:1.55;margin:13px 0}.method-heading p{color:var(--muted);font-size:12px;max-width:270px}.method-steps{display:grid;grid-template-columns:repeat(3,1fr);gap:27px;padding-top:12px}.method-step{position:relative}.method-step:before{content:"";position:absolute;top:16px;left:42px;right:0;border-top:1px dashed #555467}.method-step:last-child:before{display:none}.method-number{font:12px var(--mono);display:grid;place-items:center;width:32px;height:32px;border:1px solid #625176;border-radius:50%;color:var(--accent)}.method-step h3{font-size:14px;font-weight:550;margin:20px 0 9px}.method-step p{font-size:11px;line-height:1.95;color:var(--muted);margin:0}.cta-band{background:#2d293b;border:1px solid #544565;border-radius:10px;display:flex;align-items:center;justify-content:space-between;padding:35px 40px;gap:25px;margin-bottom:72px;position:relative;overflow:hidden}.cta-band::after{content:"{ }";position:absolute;right:235px;font:100px var(--mono);color:#bd93f90c;pointer-events:none}.cta-band h2{font-size:23px;letter-spacing:-.5px;font-weight:550;margin:0 0 7px}.cta-band p{color:var(--muted);font-size:12px;margin:0}.site-footer{border-top:1px solid var(--line);padding:28px 0 24px}.footer-top{display:flex;justify-content:space-between;gap:25px;align-items:center}.footer-note{font-size:11px;color:var(--muted);margin:10px 0 0}.footer-links{display:flex;gap:25px;font-size:11px;color:var(--muted)}.footer-links a:hover{color:var(--accent)}.footer-bottom{display:flex;justify-content:space-between;border-top:1px solid #ffffff07;margin-top:24px;padding-top:17px;font:9px var(--mono);letter-spacing:1px;color:#9195af}.footer-bottom span:last-child{color:var(--muted)}
.breadcrumb{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:10px;padding-top:30px}.breadcrumb a:hover{color:var(--accent)}.breadcrumb span[aria-hidden]{color:#747990}.page-intro{padding:46px 0 37px;max-width:750px}.page-intro h1{font-size:46px;line-height:1.4;font-weight:600;letter-spacing:-1.5px;margin:15px 0}.page-intro>p{font-size:13px;color:var(--muted);line-height:1.95;margin:0}.learning-banner{display:flex;align-items:center;justify-content:space-between;gap:30px;background:linear-gradient(105deg,#383046,#2c2d3a);border:1px solid #5c4b73;padding:26px 30px;border-radius:8px;margin:0 0 35px}.learning-banner h2{font-size:17px;font-weight:550;margin:5px 0 7px}.learning-banner p{font-size:11px;color:var(--muted);margin:0}.learning-banner .eyebrow-label{font-size:9px}.banner-progress{display:flex;gap:14px;align-items:center;min-width:180px}.progress-ring{width:53px;height:53px;flex-shrink:0;border-radius:50%;background:conic-gradient(var(--accent) var(--progress,0%),#bd93f91a 0);display:grid;place-items:center;position:relative}.progress-ring::before{content:"";position:absolute;inset:4px;border-radius:50%;background:#333041}.progress-ring span{position:relative;font:12px var(--mono)}.banner-progress p{font-size:10px}.catalog-toolbar{display:flex;justify-content:space-between;align-items:center;gap:20px;border-bottom:1px solid var(--line);margin-bottom:28px}.filter-tabs{display:flex;gap:26px}.filter-tab{background:none;color:var(--muted);padding:0 0 15px;border-bottom:2px solid transparent;font-size:12px}.filter-tab[aria-pressed=true]{color:var(--accent);border-color:var(--accent)}.catalog-count{font:10px var(--mono);color:var(--muted);padding-bottom:15px}.catalog-note{display:flex;gap:16px;align-items:flex-start;border-top:1px solid var(--line);margin-top:35px;padding-top:24px;color:var(--muted)}.catalog-note .note-icon{font:16px var(--mono);color:var(--accent);border:1px solid #625176;border-radius:5px;padding:3px 10px}.catalog-note h3{font-size:12px;font-weight:500;color:var(--fg);margin:0 0 5px}.catalog-note p{font-size:11px;margin:0;line-height:1.9}.empty-state{padding:50px 20px;text-align:center;border:1px dashed var(--line);border-radius:8px;color:var(--muted);grid-column:1/-1}.empty-state strong{color:var(--fg);display:block;font-size:16px;font-weight:500;margin-bottom:6px}.empty-state p{font-size:12px;margin:0}.catalog-section{padding-bottom:70px}.guide-layout{display:grid;grid-template-columns:190px minmax(0,1fr);gap:65px;align-items:start;padding:10px 0 75px}.guide-toc{position:sticky;top:30px;display:grid;gap:5px;padding-top:8px}.guide-toc>span{font:10px var(--mono);color:var(--muted);letter-spacing:1px;margin-bottom:12px}.guide-toc a{padding:8px 12px;border-left:1px solid var(--line);font-size:12px;color:var(--muted)}.guide-toc a:hover{border-color:var(--accent);color:var(--accent);background:#bd93f907}.guide-content{max-width:790px}.guide-section{padding-bottom:34px;margin-bottom:34px;border-bottom:1px solid var(--line);scroll-margin-top:35px}.guide-section:last-child{margin:0}.guide-section>h2{font-size:23px;font-weight:550;letter-spacing:-.5px;margin:0 0 16px;display:flex;align-items:center;gap:13px}.guide-section>h2>span{font:11px var(--mono);color:var(--accent)}.guide-section>p{font-size:13px;color:var(--muted);line-height:2}.guide-tip{border-left:2px solid var(--accent);padding:12px 20px;background:#bd93f908;margin:23px 0;color:#d2c5e4;font-size:12px}.guide-list{padding:0;list-style:none;counter-reset:guide}.guide-list li{counter-increment:guide;display:grid;grid-template-columns:27px 1fr;gap:10px;margin:20px 0;color:var(--muted);font-size:12px;line-height:1.9}.guide-list li::before{content:counter(guide,decimal-leading-zero);font:11px var(--mono);color:var(--accent);padding-top:4px}.guide-list strong{color:var(--fg);font-weight:500;display:block;margin-bottom:3px}.cheatsheet{width:100%;border-collapse:collapse;text-align:left;font-size:12px}.cheatsheet th{font-size:10px;color:var(--muted);font-weight:400;background:var(--surface)}.cheatsheet td,.cheatsheet th{padding:13px 15px;border-bottom:1px solid var(--line)}.cheatsheet td:first-child{font-family:var(--mono);color:var(--cyan);white-space:nowrap}.cheatsheet td:last-child{color:var(--muted)}.key-row{display:flex;justify-content:space-between;align-items:center;padding:12px 0;border-bottom:1px solid #ffffff07;color:var(--muted);font-size:12px}.key-row kbd{font-size:11px;border:1px solid #55596c;border-bottom-width:3px;border-radius:5px;padding:3px 9px;min-width:35px;text-align:center;color:var(--fg);background:var(--surface)}.faq details{border-bottom:1px solid var(--line);padding:17px 0}.faq summary{cursor:pointer;list-style:none;font-size:13px;display:flex;justify-content:space-between;gap:15px;align-items:center}.faq summary::-webkit-details-marker{display:none}.faq summary::after{content:"+";font:19px var(--mono);color:var(--accent)}.faq details[open] summary::after{content:"−"}.faq details p{color:var(--muted);font-size:12px;line-height:2;margin-bottom:0}.guide-bottom{display:flex;justify-content:space-between;align-items:center;gap:20px;font-size:12px;color:var(--muted);padding-top:10px}.guide-content code{background:#ffffff06;padding:2px 5px;border-radius:3px;color:var(--cyan);font-size:.9em}
/* The lesson engine stays standalone. These rules unify its surrounding layout. */
.lesson-page{background:#21222c}.lesson-page .site-header{height:88px}.lesson-page .site-nav{margin-left:52px}.lesson-page .site-header .header-inner{height:100%}.lesson-page .site-header .brand-mark{font-size:23px}.lesson-page .shell{max-width:1390px;padding-inline:46px}.lesson-page .lab-breadcrumb{padding:25px 0 0;font-size:10px;color:var(--muted);display:flex;gap:10px;align-items:center}.lesson-page .lab-breadcrumb a:hover{color:var(--accent)}.lesson-page .layout{grid-template-columns:190px minmax(0,1fr);gap:38px}.lesson-page aside{padding-top:36px}.lesson-page .side-kicker{font:9px var(--mono);letter-spacing:1.6px}.lesson-page .side-title{font-size:14px;margin-bottom:24px}.lesson-page main{padding-top:31px}.lesson-page .lesson-heading{margin-bottom:26px}.lesson-page h1{font-size:32px;letter-spacing:-.8px;margin-block:12px}.lesson-page .eyebrow{font-size:10px;letter-spacing:1.4px}.lesson-page .intro{font-size:12px;line-height:1.9}.lesson-page .lesson-duration{border:1px solid #5b4a70;padding:4px 9px;border-radius:4px;color:#c6addf;font-size:10px}.lesson-page .workspace{border-color:#505065;background:#282a36;border-radius:9px}.lesson-page .workspace-head{background:#30323f;height:47px}.lesson-page .code-panel{background:#252630}.lesson-page .detail-panel{background:#2b2d39}.lesson-page .output-panel{background:#20212b}.lesson-page .controls{background:#2d2f3d}.lesson-page .tune,.lesson-page .quiz{border-radius:8px;background:#282a36}.lesson-page .lesson-link{border-radius:6px}.lesson-page .lesson-link.active{background:#bd93f913}.lesson-page .side-bottom{border:1px solid var(--line);border-radius:7px;padding:15px 13px;margin-top:33px;font-size:10px;background:#ffffff02}.lesson-page .side-guide{display:block;margin-top:17px;color:var(--accent);font-size:11px}.lesson-page .text-button{font-size:11px}.lesson-page .site-footer{margin-top:18px}.lesson-page .site-footer .site-brand-text strong{font-size:14px}.lesson-page .site-footer .brand-mark{height:31px;width:31px;font-size:19px}.lesson-page .lab-top-actions{margin-left:auto;display:flex;gap:18px;align-items:center}
@media(min-width:1500px){.hero{gap:90px;padding-top:100px;padding-bottom:80px}.hero-copy h1{font-size:64px}.demo-line{min-height:39px;font-size:13px}}
@media(max-width:1150px){.container{width:calc(100% - 64px)}.site-nav,.lesson-page .site-nav{margin-left:15px;gap:22px}.header-actions{gap:15px}.nav-progress{display:none}.hero{gap:35px;padding-top:65px}.hero-copy h1{font-size:48px}.demo-line{font-size:11px}.method-layout{gap:35px}.method-steps{gap:18px}.course-body{padding:20px}.lesson-page .shell{padding-inline:30px}.lesson-page .layout{grid-template-columns:160px minmax(0,1fr);gap:26px}}
@media(max-width:850px){.container{width:calc(100% - 48px)}.site-header,.lesson-page .site-header{height:76px}.header-inner{gap:20px}.site-nav,.lesson-page .site-nav{margin-left:0;gap:20px}.site-brand-text strong{font-size:14px}.site-brand-text small{font-size:8px}.header-actions .button{font-size:11px;padding:9px 10px;gap:8px}.hero{gap:25px;padding:52px 0 45px}.hero-copy h1{font-size:40px;letter-spacing:-1.8px}.hero-copy>p{font-size:12px}.hero-actions{gap:9px;margin-top:24px}.hero-actions .button{font-size:11px;padding:12px 13px;gap:10px}.hero-footnote{font-size:9px;gap:10px}.demo-source{padding-top:17px}.demo-line{font-size:10px;min-height:32px}.demo-ln{width:25px;margin-right:11px}.demo-state{padding:14px}.demo-value{padding:8px}.demo-value small{font-size:8px}.demo-toolbar p{max-width:150px;font-size:9px}.demo-note{right:0;font-size:9px;padding:7px 10px}.demo-caption{font-size:9px}.stat{gap:12px;padding-left:20px}.stat strong{font-size:25px}.stat span{font-size:10px}.stat small{font-size:8px}.course-grid{gap:13px}.course-art{height:142px}.course-body{padding:17px}.course-body h3{font-size:19px}.course-body p{font-size:11px}.art-box{width:48px;height:55px}.variable-art{gap:7px}.terminal-art{width:85%;padding:10px}.loop-art{gap:5px;font-size:8px}.loop-art b{padding:8px}.method-layout{grid-template-columns:1fr;gap:18px}.method-heading p{max-width:100%}.method-steps{gap:35px}.section{padding-block:55px}.cta-band{padding:28px;margin-bottom:55px}.cta-band h2{font-size:20px}.learning-banner{gap:20px;padding:23px}.banner-progress{min-width:125px}.guide-layout{grid-template-columns:150px minmax(0,1fr);gap:35px}.lesson-page .layout{display:block}.lesson-page aside{padding:20px 0 0}.lesson-page main{padding-top:26px}.lesson-page .shell{padding-inline:24px}.lesson-page .lab-breadcrumb{padding-top:20px}.lesson-page h1{font-size:30px}}
@media(max-width:650px){.container{width:calc(100% - 36px)}.site-header,.lesson-page .site-header{height:72px}.site-brand-text strong{font-size:14px}.site-brand-text small{letter-spacing:1.8px}.brand-mark{width:34px;height:34px;font-size:21px}.menu-toggle{display:block}.header-actions{margin-left:auto;gap:12px}.header-actions>.button{display:none}.site-nav,.lesson-page .site-nav{display:none;position:absolute;top:71px;left:0;right:0;height:auto;background:var(--surface);padding:16px 18px;border-bottom:1px solid var(--line);margin:0;box-shadow:0 15px 20px #0002;gap:0;flex-direction:column;align-items:stretch}.site-nav.is-open{display:flex}.site-nav a{padding:13px 15px;height:auto;border-radius:5px}.site-nav a[aria-current=page]{background:#bd93f90c;color:var(--accent)}.site-nav a[aria-current=page]::after{display:none}.hero{grid-template-columns:1fr;padding:43px 0 39px;gap:37px}.hero-copy h1{font-size:clamp(34px,10vw,42px);margin-top:22px;letter-spacing:-1.8px}.hero-copy>p{font-size:13px;max-width:340px}.hero-actions{margin:28px 0 19px;gap:12px}.hero-actions .button{padding:13px 18px;font-size:12px;gap:18px}.hero-footnote{font-size:10px;gap:18px}.demo-wrap{margin:0 3px;padding-top:0}.demo-wrap::before{inset:-10px -15px 0}.demo-line{font-size:11px;min-height:34px}.demo-ln{width:32px;margin-right:16px}.demo-source{padding:17px 0}.demo-state{padding:16px}.demo-value{padding:9px 12px}.demo-value small{font-size:9px}.demo-toolbar p{max-width:none;font-size:10px}.demo-note{right:8px;font-size:10px}.stats-strip{gap:10px;padding-block:22px}.stat{display:block;padding-left:15px}.stat strong{font-size:24px;display:block;margin-bottom:5px}.stat span{font-size:10px;line-height:1.6;display:block}.stat small{font-size:7px;letter-spacing:.5px;margin-top:5px}.section{padding-block:45px}.section-head{gap:15px;margin-bottom:24px}.section-head h2{font-size:25px}.section-head .text-link{font-size:10px;gap:8px;white-space:nowrap;margin-bottom:4px}.eyebrow-label{font-size:9px;letter-spacing:1.7px}.course-grid{grid-template-columns:1fr;gap:20px}.course-art{height:165px}.course-body{padding:23px}.course-body h3{font-size:23px}.course-body p{font-size:12px}.art-box{width:64px;height:65px}.variable-art{gap:13px}.terminal-art{width:74%;font-size:12px}.loop-art{gap:14px;font-size:11px}.loop-art b{padding:10px 12px}.course-tags{margin-bottom:22px}.method-layout{gap:12px}.method-heading h2{font-size:26px}.method-steps{grid-template-columns:1fr;gap:24px}.method-step{display:grid;grid-template-columns:34px 1fr;column-gap:16px}.method-number{grid-row:1/3;margin-top:2px}.method-step:before{top:43px;left:16px;right:auto;bottom:-16px;border-top:0;border-left:1px dashed #555467}.method-step h3{margin:1px 0 7px}.method-step p{font-size:12px}.cta-band{padding:28px 24px;display:block;margin-bottom:45px}.cta-band h2{font-size:21px}.cta-band p{font-size:11px}.cta-band>.button{margin-top:23px}.cta-band::after{right:15px;bottom:0}.footer-top{align-items:start}.footer-note{max-width:190px;line-height:1.8;font-size:10px}.footer-links{flex-direction:column;gap:8px;font-size:10px}.footer-bottom{font-size:8px;letter-spacing:.3px;gap:15px}.footer-bottom span:last-child{text-align:right}.breadcrumb{padding-top:24px}.page-intro{padding:33px 0 29px}.page-intro h1{font-size:35px;margin-block:15px}.page-intro>p{font-size:12px}.learning-banner{flex-wrap:wrap;padding:22px;gap:22px}.learning-banner>div:first-child{flex:1;min-width:170px}.learning-banner h2{font-size:16px}.banner-progress{min-width:0}.banner-progress>div:last-child{display:none}.learning-banner>.button{width:100%;justify-content:space-between}.catalog-toolbar{gap:10px}.filter-tabs{gap:20px}.filter-tab{font-size:11px}.catalog-count{font-size:9px}.catalog-section{padding-bottom:45px}.catalog-note{gap:12px}.guide-layout{grid-template-columns:1fr;gap:28px;padding-top:0;padding-bottom:45px}.guide-toc{position:static;display:flex;overflow:auto;padding:0 0 12px;border-bottom:1px solid var(--line);gap:5px}.guide-toc>span{display:none}.guide-toc a{white-space:nowrap;border-left:0;padding:7px 10px;background:var(--surface);border-radius:4px;font-size:10px}.guide-section>h2{font-size:21px}.guide-section>p{font-size:12px}.cheatsheet td,.cheatsheet th{padding:12px 9px;font-size:10px}.guide-bottom{align-items:start;flex-direction:column}.lesson-page .shell{padding-inline:15px}.lesson-page .lab-breadcrumb{font-size:9px;gap:7px;flex-wrap:wrap}.lesson-page .lesson-heading{margin-bottom:20px}.lesson-page h1{font-size:27px}.lesson-page .site-footer .container{width:calc(100% - 30px)}.lesson-page .lab-top-actions{gap:12px}.lesson-page .nav-progress{display:none}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

.guide-toc{scrollbar-width:none}.guide-toc::-webkit-scrollbar{display:none}

/* Interaction polish: motion follows an action, then settles. */
:root{--ease-out:cubic-bezier(.22,1,.36,1);--accent-ink:#21222c}
@property --progress{syntax:'<percentage>';inherits:false;initial-value:0%}
.progress-ring{transition:--progress .6s var(--ease-out)}
.site-header{background:#21222cf5}
.brand-mark{border-radius:8px;transition:transform .3s var(--ease-out)}
.site-brand:hover .brand-mark{transform:rotate(-7deg)}
.site-nav a{transition:color .18s}
.site-nav a::before{content:'';position:absolute;left:0;right:0;bottom:24px;height:1px;background:var(--accent);transform:scaleX(0);transform-origin:left;transition:transform .25s var(--ease-out)}
.site-nav a:hover::before{transform:scaleX(1)}
.button,.btn,.demo-step,.demo-back,.quiz-choice,.lesson-link,.home-card,.next-btn{transition:background .18s,border-color .18s,color .18s,opacity .2s,box-shadow .25s,transform .25s var(--ease-out)}
.button:active,.btn:active:not(:disabled),.demo-step:active,.demo-back:active:not(:disabled),.quiz-choice:active{transform:translateY(1px) scale(.97)}
.button-primary:hover,.btn.primary:hover:not(:disabled){box-shadow:0 5px 20px #bd93f91a}
.button .arrow,.text-link .arrow,.next-btn svg,.course-card-bottom>span:first-child{transition:transform .25s var(--ease-out)}
.button:hover .arrow,.text-link:hover .arrow{transform:translate(2px,-2px)}
.next-btn:hover svg,.course-card:hover .course-card-bottom>span:first-child{transform:translateX(4px)}
.hero{gap:54px;padding-top:64px;padding-bottom:44px}
.hero-copy h1{font-weight:600;font-size:clamp(40px,4.2vw,61px);line-height:1.4;letter-spacing:-2px}
.hero-copy h1 em::after{display:none}
.hero-copy>p{max-width:440px;line-height:2.1}
.hero-footnote{opacity:.85}
.demo-wrap::before{opacity:.45}
.demo-window{border-color:#494b5d;box-shadow:0 20px 45px #10111b40}
.demo-source{padding-block:16px}
.demo-line{min-height:33px;transition:background .22s,border-color .22s}
.demo-note{transform:rotate(-2deg);background:var(--bg);border-style:dashed;color:var(--muted)}
.demo-timeline{height:2px;background:var(--line)}
.demo-timeline span{display:block;height:100%;background:var(--accent);width:0;transition:width .35s var(--ease-out)}
.demo-toolbar{flex-wrap:wrap;padding:12px 16px}
.demo-toolbar p{flex:1;min-width:140px;line-height:1.65}
.demo-step:hover{background:#cdaffa}
.demo-nav{display:flex;align-items:center;gap:10px}
.demo-back{width:29px;height:29px;border:1px solid var(--line);border-radius:5px;background:none;color:var(--muted)}
.demo-back:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.demo-dots{display:flex;gap:4px}
.demo-dots i{display:block;width:4px;height:4px;border-radius:50%;background:var(--line);transition:background .2s,transform .25s var(--ease-out)}
.demo-dots i.current{background:var(--accent);transform:scale(1.5)}
.demo-value{transition:background .25s,border-color .25s}
.demo-value.highlight{background:#bd93f90a}
.lab-principles{display:flex;align-items:center;gap:32px;border-block:1px solid var(--line);padding-block:23px;font-size:12px;color:var(--muted)}
.lab-principles b{font:10px var(--mono);color:var(--accent);margin-right:9px}
.lab-principles>a{margin-left:auto;font-size:11px;transition:color .2s}
.lab-principles>a:hover{color:var(--accent)}
.course-card{transition:transform .35s var(--ease-out),border-color .25s,box-shadow .35s;background:#272934}
.course-card:hover{box-shadow:0 12px 30px #14151d40;transform:translateY(-4px)}
.course-art{background:#2b2d39}
.art-box{transition:transform .4s var(--ease-out),background .3s}
.course-card:hover .art-box:nth-child(1){transform:translateY(-5px) rotate(-3deg)}
.course-card:hover .art-box:nth-child(3){transform:translateY(-3px) rotate(3deg);transition-delay:40ms}
.course-card:hover .art-box.result{transform:translateY(-7px);background:#bd93f925;transition-delay:80ms}
.course-card:hover .cursor{animation:lab-cursor 1s steps(2) 3}
.loop-art b{transition:transform .3s var(--ease-out),border-color .3s}
.course-card:hover .loop-art b{transform:translateY(-4px);border-color:var(--cyan)}
.course-card:hover .loop-art b:nth-of-type(2){transition-delay:65ms}
.course-card:hover .loop-art b:nth-of-type(3){transition-delay:130ms}
@keyframes lab-cursor{50%{opacity:0}}
[data-catalog]{align-content:start}
.filter-tabs{position:relative}
.filter-tab{position:relative;border-bottom:0;transition:color .2s}
.filter-tab::after{content:'';position:absolute;bottom:0;left:0;right:0;background:var(--accent);height:2px;transform:scaleX(0);transition:transform .28s var(--ease-out)}
.filter-tab[aria-pressed=true]::after{transform:scaleX(1)}
.filter-tab:hover{color:var(--fg)}
.learning-banner{background:#2c2c3a;border-color:#4c435e}
.faq summary::after{content:'+';transition:transform .25s var(--ease-out)}
.faq details[open] summary::after{content:'+';transform:rotate(45deg)}
.faq details[data-expanded=false] summary::after{transform:rotate(0)}
.faq details[data-expanded=true] summary::after{transform:rotate(45deg)}
.faq summary{transition:color .18s}
.faq summary:hover{color:var(--accent)}
.guide-toc a{transition:color .2s,border-color .2s,background .2s}
.guide-toc a.is-current{color:var(--accent);border-color:var(--accent);background:#bd93f90b}
.lesson-page .workspace{box-shadow:0 8px 28px #10111a26}
.lesson-page .workspace-head{background:#2c2e3b}
.lesson-page .controls{background:#292b37}
.lesson-page .code-panel{position:relative}
.lesson-page .code-list{position:relative;isolation:isolate}
.code-row{transition:background .2s,border-color .2s,box-shadow .2s}
.lesson-page .code-row.executed{background:transparent;border-left-color:transparent}
.execution-marker{position:absolute;left:0;right:0;top:0;border-left:3px solid var(--accent);background:#bd93f916;pointer-events:none;z-index:-1;transition:transform .28s var(--ease-out),height .28s var(--ease-out),opacity .18s}
.lesson-page .code-row.selected{background:#bd93f90d}
.lesson-link.active::before{content:'';position:absolute;left:0;top:18%;bottom:18%;width:2px;background:var(--accent);border-radius:2px}
.variable-grid{position:relative;align-items:stretch;min-height:57px}
.variable{transition:border-color .25s,background .25s;min-width:0}
.variable.changed{background:#8be9fd09;border-color:#8be9fd80}
.variable-value{font-variant-numeric:tabular-nums;flex-wrap:wrap}
.old-value{font-size:10px;white-space:nowrap}
.terminal-line{display:block;min-height:1.85em}
.quiz-choice{position:relative}
.quiz-choice.correct{background:#50fa7b0b}
.quiz-choice.correct::after{content:'✓';position:absolute;right:8px;top:50%;transform:translateY(-50%);font-size:11px}
.quiz-choice.wrong{background:#ffb86c08}
.quiz-feedback{line-height:1.9}
.quiz:has(.quiz-feedback.good){border-color:#50fa7b55;transition:border-color .3s}
.lesson-page .range-row input{appearance:none;background:transparent;height:28px}
.range-row input::-webkit-slider-runnable-track{height:4px;background:linear-gradient(to right,var(--accent) var(--range-progress,28.57%),var(--line) 0);border-radius:4px}
.range-row input::-webkit-slider-thumb{appearance:none;width:15px;height:15px;margin-top:-5.5px;background:var(--fg);border:3px solid var(--accent);border-radius:50%;transition:box-shadow .2s,transform .2s}
.range-row input:hover::-webkit-slider-thumb{box-shadow:0 0 0 5px #bd93f91a}
.range-row input:active::-webkit-slider-thumb{transform:scale(1.15);box-shadow:0 0 0 7px #bd93f91a}
.range-row input::-moz-range-track{height:4px;background:var(--line);border-radius:4px}
.range-row input::-moz-range-progress{height:4px;background:var(--accent)}
.range-row input::-moz-range-thumb{width:10px;height:10px;background:var(--fg);border:3px solid var(--accent);border-radius:50%}
.range-value{font-variant-numeric:tabular-nums}
.motion-ghost,.motion-ghost *{pointer-events:none!important;user-select:none!important}
@media(max-width:850px){.lab-principles{gap:20px;font-size:11px}.lab-principles>a{font-size:10px}.demo-nav{gap:7px}.demo-toolbar p{min-width:110px}.demo-dots{display:none}}
@media(max-width:650px){.site-nav a::before{display:none}.hero{gap:30px;padding:38px 0 35px}.hero-copy h1{font-size:clamp(34px,10vw,42px);letter-spacing:-1.5px}.hero-copy>p{font-size:12px}.lab-principles{flex-wrap:wrap;gap:13px 20px;padding-block:20px}.lab-principles>span{font-size:10px}.lab-principles b{margin-right:5px}.lab-principles>a{width:100%;margin-left:0;padding-top:5px}.demo-toolbar p{font-size:10px;min-width:120px}.demo-dots{display:flex}.demo-source{padding-block:14px}.demo-note{font-size:9px}.execution-marker{transition-duration:.2s}.quiz-choice.correct::after{right:5px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}