:root{color-scheme:light dark;--navy: light-dark(#111827, #080d17);--navy-2: light-dark(#1b2638, #111827);--bg: light-dark(#f5f3ef, #0c111c);--surface: light-dark(#fffdf9, #151c29);--surface-2: light-dark(#eeeae3, #1d2737);--text: light-dark(#18202c, #f7f3ed);--muted: light-dark(#454e5c, #b7c0cc);--border: light-dark(#ddd8cf, #303b4d);--danger: light-dark(#a4312a, #ff9e96);--warning: light-dark(#8a570c, #f4bd65);--code-bg: #09101b;--code-text: #e8eef7;--accent: light-dark(#176b45, #7ae1ac);--accent-soft: light-dark(#dcf3e5, #153728);--radius-sm: 8px;--radius-md: 14px;--radius-lg: 22px;--shadow: 0 20px 54px rgba(17, 24, 39, .13);font-family:Inter,Pretendard,Noto Sans KR,system-ui,sans-serif;font-synthesis:none}*{box-sizing:border-box}html{min-width:320px;background:var(--bg);scroll-behavior:smooth}body{margin:0;color:var(--text);background:var(--bg)}button,input,select{font:inherit}button,summary,a{-webkit-tap-highlight-color:transparent}a{color:inherit}button{cursor:pointer}.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}.skip-link{position:fixed;z-index:100;top:-50px;left:20px;padding:10px 14px;color:#fff;background:var(--accent);border-radius:0 0 8px 8px}.skip-link:focus{top:0}.app-shell{min-height:100vh}.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:20px;min-height:70px;padding:10px clamp(16px,3vw,38px);color:#fff;background:var(--navy);border-bottom:3px solid var(--accent)}.brand{display:flex;align-items:center;gap:11px;color:#fff;text-decoration:none;white-space:nowrap}.brand-mark{display:block;flex:0 0 40px;width:40px;height:40px;border-radius:10px}.brand h1{margin:0;color:#fff;font:700 18px/1.2 Inter,Pretendard,Noto Sans KR,system-ui,sans-serif;letter-spacing:-.02em}.topbar-actions{display:flex;align-items:center;gap:16px;margin-left:auto}.subject-badge{color:#c9d3df;font-size:12px;white-space:nowrap}.progress-summary{color:#c9d3df;font-size:14px;white-space:nowrap;text-decoration:none}.language-switcher{padding:8px 10px;color:#c9d3df;background:transparent;border:1px solid #465268;border-radius:8px;font-size:12px;font-weight:800}.language-switcher option{color:var(--text);background:var(--surface)}.search-palette{position:relative}.search-palette summary{display:flex;align-items:center;gap:6px;cursor:pointer;padding:8px 12px;border:1px solid #465268;border-radius:8px;font-size:12px;font-weight:800;list-style:none}.search-palette summary:after{content:"▾";font-size:10px;transition:transform .15s}.search-palette[open] summary:after{transform:rotate(180deg)}.search-popover{position:absolute;z-index:50;top:44px;right:0;width:min(520px,calc(100vw - 32px));padding:16px;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md);box-shadow:var(--shadow)}.search-popover label{display:grid;gap:7px;font-size:12px;font-weight:800}.search-popover input{width:100%;padding:12px;color:var(--text);background:var(--bg);border:1px solid var(--border);border-radius:8px}.search-popover>div{display:grid;margin-top:10px}.search-popover a{display:grid;grid-template-columns:42px 1fr;gap:8px;padding:9px;border-top:1px solid var(--border);text-decoration:none}.search-popover small{color:var(--accent);font-weight:900}.search-popover span{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.app-body{display:grid;grid-template-columns:230px minmax(0,1fr);min-height:calc(100vh - 70px)}.primary-nav{position:sticky;top:70px;align-self:start;min-height:calc(100vh - 70px);padding:24px 14px;color:#e6edf5;background:var(--navy-2);border-right:1px solid var(--border)}.nav-label{margin:26px 12px 8px;color:var(--muted);font-size:10px;font-weight:900;text-transform:uppercase;letter-spacing:.12em}.primary-nav>a{display:block;margin:3px 0;padding:11px 12px;color:#b8c1cf;border-radius:8px;text-decoration:none;font-size:14px;font-weight:720}.primary-nav>a:hover{color:#fff;background:#273347}.primary-nav>a.active{color:#fff;background:var(--accent)}.course-switcher{position:relative;margin-bottom:16px}.course-switcher summary{display:flex;justify-content:space-between;padding:12px;color:#c9d3df;background:transparent;border:1px solid #465268;border-radius:9px;cursor:pointer;font-size:12px;font-weight:900;list-style:none}.course-switcher[open]>div{display:grid;gap:4px;margin-top:6px;padding:8px;overflow:hidden;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:10px}.course-switcher a{padding:9px 10px;color:var(--text);border-radius:7px;text-decoration:none;font-size:13px}.course-switcher a:hover{background:var(--surface-2)}.course-switcher a[aria-current=true]{color:var(--accent);background:var(--accent-soft);font-weight:900}#main-content{min-width:0;padding:clamp(24px,4vw,58px)}.page{width:min(1380px,100%);margin:0 auto}.page-stack{display:grid;width:min(1180px,100%);grid-template-columns:minmax(0,1fr);gap:54px;margin:0 auto}.page-header{max-width:900px;margin-bottom:34px}.page-header h2,.learning-hero h2,.lab-hero h2{margin:8px 0 18px;font-size:clamp(38px,5vw,64px);line-height:1.05;letter-spacing:-.045em}.page-header>p:last-child{color:var(--muted);font-size:18px;line-height:1.75}.eyebrow{margin:0 0 8px;color:var(--accent);font-size:11px;font-weight:950;text-transform:uppercase;letter-spacing:.12em}.learning-hero{display:grid;min-width:0;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);gap:clamp(28px,5vw,70px);align-items:center;padding:clamp(30px,6vw,80px) 0}.learning-hero>div{min-width:0}.learning-hero .eyebrow{margin-bottom:10px;font-size:14px;font-weight:700;text-transform:none;letter-spacing:0}.learning-hero h2{margin:0;max-width:22ch;font-size:clamp(32px,3.2vw,48px);line-height:1.12;letter-spacing:-.04em;word-break:keep-all;overflow-wrap:normal;text-wrap:balance}.learning-hero>div:first-child>p:not(.eyebrow){max-width:620px;color:var(--muted);font-size:18px;line-height:1.7}.hero-actions{display:flex;flex-wrap:wrap;gap:18px;align-items:center;margin-top:28px}.primary-button{display:inline-block;padding:13px 18px;color:#fff;background:var(--accent);border:0;border-radius:9px;font-weight:900;text-decoration:none}.primary-button:disabled{opacity:.65;cursor:default}.secondary-link{color:var(--accent);font-weight:850;text-decoration:none}.hero-visual{display:grid;width:100%;max-width:520px;gap:16px;justify-self:end}.hero-visual>img{display:block;width:100%;height:auto;aspect-ratio:16 / 9;object-fit:contain;background:#0a0f18;border:1px solid #354157;border-radius:var(--radius-lg);box-shadow:var(--shadow)}.hero-terminal{display:grid;min-width:0;gap:6px;overflow:hidden;padding:20px;color:#e8eef7;background:#070c14;border:1px solid #354157;border-radius:14px;box-shadow:var(--shadow);font:13px/1.55 ui-monospace,monospace;transform:rotate(.6deg);transform-origin:center top}.hero-terminal span{color:#f58b64;font-weight:900}.hero-terminal strong{color:#7ae1ac}.stat-row{display:grid;grid-template-columns:repeat(4,1fr);overflow:hidden;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md)}.stat-row div{display:flex;gap:8px;align-items:baseline;justify-content:center;padding:20px 24px;color:var(--text);border-right:1px solid var(--border)}.stat-row div:last-child{border:0}.stat-row strong{font-size:29px}.stat-row span{color:var(--muted);font-size:12px;font-weight:800}.section-heading h3{margin:6px 0 24px;font-size:clamp(28px,3vw,42px);letter-spacing:-.03em}.lab-card-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.lab-card{display:grid;grid-template-rows:auto auto 1fr auto;min-height:245px;padding:22px;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md);text-decoration:none;transition:transform .18s ease,box-shadow .18s ease}.lab-card:hover{transform:translateY(-3px);box-shadow:var(--shadow)}.lab-card>span{color:var(--accent);font-size:10px;font-weight:950;letter-spacing:.1em}.lab-card h4{margin:15px 0 10px;font-size:20px;line-height:1.35}.lab-card p{color:var(--muted);font-size:13px;line-height:1.65}.lab-card b{color:var(--accent);font-size:12px}.curriculum-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:15px}.chapter-card{display:grid;min-width:0;grid-template-columns:auto minmax(0,1fr);gap:18px;padding:22px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md)}.chapter-card>div{min-width:0}.chapter-card h4,.chapter-card p,.chapter-card a{overflow-wrap:anywhere}.chapter-number{display:grid;place-items:center;width:48px;height:48px;color:#06150e;background:#7ae1ac;border-radius:12px;font-weight:950}.chapter-card h4{margin:2px 0 7px;font-size:21px}.chapter-card>div>p{min-height:42px;margin:0;color:var(--muted);font-size:13px;line-height:1.55}.chapter-card ol{margin:18px 0 0;padding:0;list-style:none}.chapter-card li{display:grid;grid-template-columns:1fr auto;gap:10px;padding:10px 0;border-top:1px solid var(--border)}.chapter-card a{text-decoration:none;font-weight:750}.chapter-card li span{color:var(--muted);font-size:11px}.meta-row{display:flex;flex-wrap:wrap;gap:8px}.meta-row span{padding:7px 9px;color:var(--muted);background:var(--surface-2);border-radius:7px;font-size:12px}.lesson-page{max-width:980px}.lesson-page>section{margin:34px 0}.lesson-objectives,.lesson-check{padding:24px;background:var(--surface-2);border:1px solid var(--border);border-radius:var(--radius-md)}.lesson-objectives li,.lesson-section p,.lesson-section li{line-height:1.75}.lesson-section h3{margin-bottom:8px;font-size:25px}.lesson-section pre{overflow-x:auto;padding:18px;color:var(--code-text);background:var(--code-bg);border-radius:10px;font:13px/1.7 ui-monospace,monospace}.lesson-section aside{padding:13px 15px;color:var(--muted);background:var(--surface-2);border-left:4px solid var(--accent)}.sources small{display:block;color:var(--muted)}.anatomy-stack{display:grid;gap:10px}.command-card{display:grid;gap:15px;padding:20px;background:var(--surface);border:1px solid var(--border);border-radius:12px}.command-card.compact{padding:16px}.command-heading{display:flex;gap:12px;align-items:flex-start;justify-content:space-between}.command-heading code{overflow-wrap:anywhere;color:var(--code-text);background:var(--code-bg);padding:8px 10px;border-radius:7px;font-size:12px}.risk{flex:none;padding:5px 7px;border-radius:6px;font-size:10px;font-weight:950}.risk-read-only{color:#176b45;background:#dcf3e5}.risk-changes-system{color:#73470d;background:#ffedc7}.risk-high-load,.risk-dangerous{color:#8c2924;background:#ffdeda}.command-card>p,.command-card section p{margin:0;color:var(--muted);line-height:1.6}.command-card section{padding-top:12px;border-top:1px solid var(--border)}.command-card section h4{margin:0 0 6px}.favorite-button{justify-self:start;padding:8px 10px;color:var(--accent);background:transparent;border:1px solid var(--border);border-radius:7px}.quiz-card{padding:20px;background:var(--surface);border:1px solid var(--border);border-radius:12px}.quiz-card h4{font-size:18px;line-height:1.5}.quiz-card>div{display:grid;grid-template-columns:1fr 1fr;gap:8px}.quiz-card button,.photo-question>button{padding:11px;color:var(--text);text-align:left;background:var(--surface-2);border:1px solid var(--border);border-radius:8px}.quiz-card button[aria-pressed=true],.photo-question>button[aria-pressed=true]{border-color:var(--accent);box-shadow:inset 3px 0 var(--accent)}.quiz-card aside,.photo-question aside{margin-top:12px;padding:12px;border-radius:8px}.quiz-card aside p{margin:5px 0 0}.correct,.success-note{background:var(--accent-soft)}.wrong,.fault-note{background:light-dark(#ffded8,#3d231f)}.lesson-check>.primary-button{margin-top:14px}.lesson-check>p{color:var(--muted);font-size:12px}.sources li{margin:10px 0}.tabs{display:flex;flex-wrap:wrap;gap:7px;padding:6px;background:var(--surface-2);border-radius:11px}.tabs button{padding:11px 15px;color:var(--muted);background:transparent;border:0;border-radius:8px;font-weight:850}.tabs button[aria-selected=true]{color:#fff;background:var(--accent)}.architecture-layout{display:grid;grid-template-columns:minmax(320px,.85fr) minmax(0,1.15fr);gap:22px;align-items:start}.component-map{display:grid;gap:14px}.component-map>section{padding:16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md)}.component-map h3{margin:0 0 10px;color:var(--muted);font-size:11px;text-transform:uppercase;letter-spacing:.08em}.component-map section>div{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:7px}.component-map button{display:grid;gap:5px;min-height:90px;padding:12px;color:var(--text);text-align:left;background:var(--surface-2);border:1px solid transparent;border-radius:8px}.component-map button[aria-pressed=true]{color:#fff;background:var(--accent)}.component-map button span{opacity:.8;font-size:11px;line-height:1.4}.component-detail{position:sticky;top:92px;padding:26px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow)}.component-detail h2{margin:6px 0 12px;font-size:38px}.component-detail .lead{font-size:18px;font-weight:750;line-height:1.6}.component-detail p,.component-detail li{line-height:1.6}.tool-panel{padding:clamp(20px,3vw,35px);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg)}.designer-layout{display:grid;grid-template-columns:minmax(310px,.7fr) minmax(0,1.3fr);gap:22px;align-items:start}.designer-form{display:grid;grid-template-columns:1fr 1fr;gap:13px;padding:18px;background:var(--surface-2);border-radius:12px}.designer-form label,.topology-controls label,.filter-bar label{display:grid;gap:6px;color:var(--muted);font-size:11px;font-weight:900}.designer-form select,.designer-form input[type=range],.topology-controls select,.filter-bar input,.filter-bar select{width:100%;padding:10px;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:7px}.designer-form .check,.topology-controls .check{display:flex;gap:8px;align-items:center}.design-result{padding:23px;border:1px solid var(--accent);border-radius:13px}.design-result.unsupported{border-color:var(--danger)}.design-result h4{margin:7px 0;font-size:28px}.design-result>p{color:var(--muted)}.design-result section{padding-top:8px;border-top:1px solid var(--border)}.design-result h5{margin:10px 0 3px;font-size:13px}.design-result li{margin:6px 0;line-height:1.45}.topology-controls{display:flex;flex-wrap:wrap;gap:15px;margin-bottom:20px}.topology-stage{display:grid;gap:10px;min-height:420px;padding:30px;color:#fff;background:#07101d;border:1px solid #334359;border-radius:15px}.spines,.leaves,.nodes{display:flex;gap:12px;justify-content:center}.spines span,.leaves span{display:grid;place-items:center;min-width:150px;padding:15px;background:#245741;border:1px solid #75dfa9;border-radius:8px;font-weight:900}.leaves span{background:#243650;border-color:#819bc1}.fabric-lines{position:relative;display:flex;gap:130px;justify-content:center;height:60px}.fabric-lines i{width:3px;height:60px;background:#7ae1ac;transform:rotate(18deg)}.fabric-lines i:nth-child(2){transform:rotate(-18deg)}.fabric-lines .fault{width:5px;background:#f36f61;border:1px dashed white;cursor:pointer}.nodes{align-items:stretch;flex-wrap:wrap}.nodes article{display:grid;min-width:145px;padding:13px;background:#151f2e;border:1px solid #41516a;border-radius:8px;text-align:center}.nodes small{color:#aebace}.topology-metrics,.progress-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin-top:12px}.topology-metrics article,.progress-stats article{display:grid;gap:5px;padding:16px;color:#fff;background:var(--navy);border-radius:9px}.topology-metrics strong,.progress-stats span{color:#7ae1ac;font-size:24px}.tool-panel>aside{margin-top:12px;padding:13px;border-radius:8px}.filter-bar{display:grid;grid-template-columns:1fr 240px;gap:13px}.result-count{color:var(--muted);font-size:12px}.command-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:13px}.back-link{color:var(--accent);font-weight:900;text-decoration:none}.lab-hero{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(280px,.8fr);gap:22px}.lab-hero h2{margin:9px 0;font-size:clamp(36px,5vw,60px);line-height:1}.lab-hero p{color:var(--muted);font-size:18px;line-height:1.6}.objective-card{padding:20px;background:var(--accent-soft);border-radius:var(--radius-md)}.terminal-lab{overflow:hidden;background:#070c14;border:1px solid #354157;border-radius:var(--radius-lg);box-shadow:var(--shadow)}.terminal-lab>header{display:flex;align-items:center;gap:12px;padding:13px 17px;color:#eef4fc;background:#141d2b}.terminal-lab>header>div{display:flex;gap:5px}.terminal-lab i{width:9px;height:9px;background:#7ae1ac;border-radius:50%}.terminal-lab i:nth-child(2){background:#f4bd65}.terminal-lab i:nth-child(3){background:#f58b64}.terminal-lab header button{margin-left:auto;padding:7px 10px;color:#fff;background:#253247;border:1px solid #45526a;border-radius:7px}.simulation-notice{margin:0;padding:10px 17px;color:#ffd1b5;background:#3b211a}.lab-progress{display:flex;justify-content:space-between;padding:9px 17px;color:#b8c4d5;border-bottom:1px solid #303c50}.lab-progress strong{color:#7ae1ac}.terminal-screen{min-height:320px;max-height:560px;overflow:auto;padding:18px;color:#e8eef7;font:13px/1.65 ui-monospace,monospace}.terminal-entry{margin-bottom:19px}.terminal-entry p{margin:0}.terminal-entry p span{color:#f4bd65}.terminal-entry pre{color:#7ae1ac;white-space:pre-wrap}.terminal-entry small{color:#b6c2d5}.terminal-placeholder{color:#7f8b9f}.terminal-tools{display:grid;grid-template-columns:1.3fr .7fr;gap:20px;padding:18px;color:#dce4f0;background:#101824;border-top:1px solid #303c50}.terminal-tools h3{margin-top:0;font-size:14px}.terminal-tools code{color:#ffd1b5}.terminal-tools p{color:#b7c2d3}.terminal-tools button{padding:10px 12px;color:#06150e;background:#7ae1ac;border:0;border-radius:7px;font-weight:900}.photo-lab{display:grid;grid-template-columns:minmax(0,1.35fr) minmax(310px,.65fr);gap:18px;align-items:start}.photo-stage,.photo-question{padding:18px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md)}.photo-image{position:relative;display:grid;place-items:center;min-height:440px;overflow:auto;background:#070c14;border-radius:10px}.photo-image img{display:block;max-width:100%;max-height:520px;object-fit:contain}.photo-image span{position:absolute;padding:6px 8px;color:#fff;background:#176b45ed;border:1px solid #7ae1ac;border-radius:6px;font-size:10px;font-weight:900;transform:translate(-50%,-50%)}.photo-stage>p{margin-bottom:5px;font-weight:900}.photo-stage>small{color:var(--muted);line-height:1.5}.photo-question{display:grid;gap:9px}.photo-question h3{font-size:24px;line-height:1.35}.photo-question>div{display:flex;justify-content:space-between;margin-top:10px}.photo-question>div button{padding:9px 12px}.troubleshooting-layout{display:grid;grid-template-columns:minmax(270px,.7fr) minmax(0,1.3fr);gap:18px;align-items:start}.case-list{display:grid;max-height:750px;overflow:auto;background:var(--surface);border:1px solid var(--border);border-radius:12px}.case-list button{display:grid;gap:6px;padding:14px;color:var(--text);text-align:left;background:transparent;border:0;border-bottom:1px solid var(--border)}.case-list button.selected{background:var(--accent-soft)}.case-list span{color:var(--accent);font-size:10px;font-weight:950}.runbook{padding:27px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg)}.runbook>h3{margin-top:5px;font-size:26px}.runbook section{margin-top:18px;padding-top:15px;border-top:1px solid var(--border)}.runbook li,.runbook p{line-height:1.65}.evidence-panel{padding:16px!important;background:var(--surface-2);border:0!important;border-left:4px solid var(--accent)!important}.relationship-card{display:grid;grid-template-columns:minmax(320px,.75fr) minmax(0,1.25fr);gap:30px;align-items:center;padding:30px;color:#fff;background:var(--navy);border-radius:var(--radius-lg)}.relationship-card h3{font-size:28px}.relationship-card p{color:#c2ccda;line-height:1.7}.protocol-stack{display:grid;gap:7px;text-align:center}.protocol-stack>*{padding:10px;background:#1c2a3e;border:1px solid #46566d;border-radius:7px}.protocol-stack>div{display:grid;grid-template-columns:.7fr 1.3fr;gap:7px;padding:0;background:none;border:0}.protocol-stack i{padding:12px;color:#08140e;background:#7ae1ac;border-radius:7px;font-style:normal;font-weight:900}.comparison-table{overflow:hidden;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-md)}.comparison-table>div{display:grid;grid-template-columns:.55fr 1fr 1fr}.comparison-table>div>*{margin:0;padding:15px;border-right:1px solid var(--border);line-height:1.55}.comparison-table>div+div{border-top:1px solid var(--border)}.comparison-table p{color:var(--muted)}.comparison-head{color:#fff;background:var(--navy)}.decision-guide{padding:27px;background:var(--accent-soft);border-radius:var(--radius-lg)}.decision-guide>div{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.decision-guide p{padding:15px;background:var(--surface);border-radius:8px;line-height:1.6}.decision-guide strong{display:block;color:var(--accent)}.decision-guide small{color:var(--muted)}.progress-stats{grid-template-columns:repeat(3,1fr)}.course-progress-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:11px}.course-progress-grid article{display:grid;gap:10px;padding:17px;background:var(--surface);border:1px solid var(--border);border-radius:9px}.course-progress-grid article>div{display:flex;justify-content:space-between}.course-progress-grid progress{width:100%;accent-color:var(--accent)}.course-progress-grid a{color:var(--accent);font-weight:900;text-decoration:none}.reset-zone{padding:20px;border:1px solid var(--border);border-radius:var(--radius-md)}.reset-zone button{margin-right:7px;padding:10px 13px}.reset-zone .danger-button{color:#fff;background:#a52c26;border:0}.empty-state{padding:30px;color:var(--muted);background:var(--surface);border-radius:10px}@media(max-width:1200px){.lab-card-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.photo-lab{grid-template-columns:1fr}}@media(max-width:1000px){.architecture-layout,.designer-layout,.troubleshooting-layout{grid-template-columns:1fr}.component-detail{position:static}.command-grid,.relationship-card{grid-template-columns:1fr}}@media(max-width:900px){.topbar{gap:10px}.topbar-actions{gap:8px}.progress-summary,.subject-badge{display:none}.language-switcher{max-width:92px}.app-body{grid-template-columns:1fr}.primary-nav{position:sticky;z-index:15;top:70px;display:flex;gap:4px;min-height:0;overflow-x:auto;padding:8px 12px;border-right:0;border-bottom:1px solid var(--border)}.nav-label{display:none}.primary-nav>a{white-space:nowrap}.course-switcher{flex:none;margin:0 5px 0 0}.course-switcher summary{height:100%;align-items:center;gap:9px}.learning-hero{grid-template-columns:1fr}.hero-visual{max-width:640px;justify-self:start}.curriculum-grid{grid-template-columns:minmax(0,1fr)}.comparison-table{overflow-x:auto}.comparison-table>div{min-width:760px}.decision-guide>div{grid-template-columns:1fr}}@media(max-width:720px){#main-content{padding:28px 18px 60px}.page-header h2{font-size:clamp(30px,10vw,42px);overflow-wrap:anywhere}.topbar{padding:9px 16px}.brand h1{font-size:14px}.brand-mark{flex-basis:36px;width:36px;height:36px}.stat-row{grid-template-columns:repeat(2,1fr)}.stat-row div:nth-child(2){border-right:0}.stat-row div:nth-child(-n+2){border-bottom:1px solid #354157}.lab-card-grid,.topology-metrics,.progress-stats,.course-progress-grid,.designer-form,.filter-bar,.lab-hero,.terminal-tools{grid-template-columns:1fr}.component-map section>div{grid-template-columns:1fr}.photo-image{min-height:300px}.quiz-card>div{grid-template-columns:1fr}.hero-terminal{transform:none}}@media(max-width:480px){.learning-hero h2{font-size:clamp(24px,7.5vw,34px)}.hero-visual>img{height:auto}.chapter-card{grid-template-columns:minmax(0,1fr)}.chapter-number{width:42px;height:42px}.topology-stage{padding:18px}.spines span,.leaves span{min-width:110px}.photo-image span{font-size:8px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}.course-switcher>div>a,.course-switcher>div>span{display:grid;grid-template-columns:25px minmax(0,1fr) auto;gap:7px;align-items:center}.course-switcher>div>a b,.course-switcher>div>span b{color:var(--accent);font-size:10px}.course-switcher>div>span[aria-disabled=true]{padding:9px 10px;color:var(--muted);border-radius:7px;font-size:12px;opacity:.78}.course-switcher>div>span small{font-size:9px;white-space:nowrap}.course-switcher[open]>div{max-height:min(68vh,560px);overflow-y:auto}