:root{color-scheme:dark;--paper:#0c1423;--panel:#131f32;--ink:#edf3fa;--muted:#acbcd0;--line:#ffffff18;--blue:#8dcfff;--mint:#b5efd1;--gold:#ffd18c;--max:1120px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:90px}body{margin:0;background:radial-gradient(ellipse at 85% 0,#18324580,transparent 32%),var(--paper);color:var(--ink);font:17px/1.9 system-ui,-apple-system,"Segoe UI","Microsoft JhengHei",sans-serif}a{color:var(--blue);text-underline-offset:5px}button,input{font:inherit}button,a,input{touch-action:manipulation}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--gold);outline-offset:5px}button:disabled{opacity:.4;cursor:default}.wrap{width:min(var(--max),calc(100% - 48px));margin:auto}.site-header{display:flex;justify-content:space-between;align-items:center;gap:24px;padding:24px 0;border-bottom:1px solid 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0;margin-bottom:20px;border-block:1px solid var(--line)}.toc a{font-size:13px;color:var(--muted);text-decoration:none}.toc a:hover{color:var(--mint)}.toc a span{color:var(--mint);margin-right:7px;font-size:11px}.lesson{padding:52px 0 58px;border-bottom:1px solid var(--line)}.lesson h2{font-size:clamp(26px,3vw,36px);line-height:1.5;letter-spacing:-.025em;margin:14px 0 20px;text-wrap:balance}.lesson>p{max-width:78ch;color:var(--muted)}.lesson h3{font-size:20px;line-height:1.6}.note{font-size:13px!important;color:var(--muted);line-height:1.8}.ref{font-size:12px;margin-left:7px;text-decoration:none}.wire-figure{margin:32px 0 24px}.wire-board{display:grid;grid-template-columns:150px minmax(0,1fr) 150px;gap:22px;align-items:center;background:var(--panel);border:1px solid var(--line);padding:32px;border-radius:22px}.device-box{display:flex;align-items:center;flex-direction:column;gap:12px;text-align:center;font-size:15px;font-weight:700;min-width:0}.device-box svg{width:70px;height:90px;color:var(--ink)}.wire-paths{display:grid;gap:22px}.wire{position:relative;text-align:center;line-height:1.5;font-size:13px}.wire span{display:inline-block;padding:0 12px 6px;color:var(--ink)}.wire b{display:block;width:100%;height:3px;background:var(--blue);position:relative;border-radius:8px}.wire b:after{content:"";position:absolute;right:-1px;top:-4px;border-block:5px solid transparent;border-left:10px solid var(--blue)}.wire.return b{background:#8d9baa}.wire.return b:after{right:auto;left:-1px;border-left:0;border-right:10px solid #8d9baa}.wire.cc b{height:3px;background:repeating-linear-gradient(90deg,var(--mint) 0 9px,transparent 9px 15px)}.wire.cc b:after{border-left-color:var(--mint)}.wire.cc b:before{content:"";position:absolute;left:-1px;top:-4px;border-block:5px solid transparent;border-right:10px solid var(--mint)}.wire-figure figcaption{margin-top:13px;max-width:95ch}.cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;margin:28px 0}.info-card{padding:24px;border:1px solid var(--line);background:var(--panel);border-radius:18px;min-width:0}.info-card p{font-size:14px;color:var(--muted);line-height:1.95;margin:12px 0 0}.info-card .term{font-size:12px;color:var(--mint);font-weight:700;letter-spacing:.08em}.info-card h3{margin:10px 0 0}.callout{border-left:3px solid var(--mint);padding:22px 26px;background:#b5efd10a;border-radius:0 16px 16px 0;margin-top:30px}.callout h3{margin:0 0 10px}.callout p{margin:0;font-size:15px;color:var(--muted)}.unit-symbol{font-size:56px;font-weight:750;line-height:1.2;color:var(--blue)}.units .info-card:nth-child(2) .unit-symbol{color:var(--mint)}.units .info-card:nth-child(3) .unit-symbol{color:var(--gold)}.units .meaning{font-weight:700;color:var(--ink)}.calculator{display:grid;grid-template-columns:1fr 1fr .85fr;gap:28px;align-items:center;padding:28px;background:var(--panel);border:1px solid var(--line);border-radius:20px}.calculator label{display:grid;gap:12px;font-size:14px;color:var(--muted)}.calculator input{width:100%;accent-color:var(--mint);min-height:28px}.calculator output{font-size:27px;font-weight:750;color:var(--ink)}.calculator .answer{border-left:1px solid var(--line);padding-left:28px}.answer span{display:block;font-size:12px;color:var(--muted)}.answer strong{display:block;color:var(--gold);font-size:38px;line-height:1.5;font-variant-numeric:tabular-nums}.formula{font-size:13px!important;margin:0!important;color:var(--muted)}.conversation{display:grid;grid-template-columns:1.2fr .8fr;gap:24px;margin-top:30px;align-items:start}.steps{display:grid;gap:12px}.step{display:grid;grid-template-columns:30px minmax(0,1fr);gap:14px;border:1px solid var(--line);padding:20px;border-radius:18px;background:var(--panel)}.step-count{width:28px;height:28px;font-size:12px;border:1px solid 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.voltage{font-size:clamp(38px,4.4vw,62px);line-height:1.5;font-weight:750;letter-spacing:-.04em;color:var(--mint);font-variant-numeric:tabular-nums}.demo-console .stage{font-size:12px;color:var(--muted);margin:0}.demo-console .console-title{margin:18px 0 10px;font-size:20px;line-height:1.5}.demo-console .note{margin:10px 0 0}.demo-controls{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px}.demo-controls[hidden]{display:none}.demo-controls .button{font-size:13px;padding:11px 15px}.demo-controls .primary{flex:1}.summary-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-top:28px}.summary-grid .callout{margin:0}.summary-grid .callout:nth-child(2){border-color:var(--gold);background:#ffd18c08}.team{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;margin:30px 0}.team article{position:relative;text-align:center;border:1px solid var(--line);padding:24px 20px;border-radius:18px;background:var(--panel)}.team 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h2{font-size:28px;line-height:1.6;margin:0 0 16px}.next-steps p{color:var(--muted);max-width:80ch}.next-steps .hero-actions{margin-top:24px}.sources{font-size:13px;line-height:1.9;color:var(--muted);padding-bottom:40px}.sources h2{font-size:18px;color:var(--ink)}.sources p{max-width:95ch}.sources li{margin-bottom:8px;overflow-wrap:anywhere}.site-footer{display:flex;justify-content:space-between;flex-wrap:wrap;gap:14px;padding:24px 0 35px;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}.skip{position:fixed;top:0;left:20px;transform:translateY(-150%);padding:10px;background:var(--mint);color:#10281f;z-index:10}.skip:focus{transform:none}
@media(max-width:850px){.hero{grid-template-columns:1fr;gap:32px;padding-top:45px}.takeaway{transform:none;display:grid;grid-template-columns:1fr auto;gap:12px 28px;padding:25px}.takeaway .section-number{grid-column:1/-1}.takeaway p{font-size:21px;margin:0}.takeaway-number{font-size:50px;align-self:center}.takeaway small{grid-column:1/-1}.conversation{grid-template-columns:1fr}.demo-console{position:static;grid-row:1}.cards{gap:12px}.info-card{padding:20px}.calculator{gap:20px}.wire-board{grid-template-columns:110px minmax(0,1fr) 110px;padding:24px;gap:18px}.summary-grid{grid-template-columns:1fr}.hero h1{font-size:50px}}
@media(max-width:600px){body{font-size:16px}.wrap{width:calc(100% - 32px)}.site-header{gap:16px;align-items:flex-start;flex-wrap:wrap;padding:18px 0}.brand{font-size:12px}.languages{max-width:100%;justify-content:flex-start;gap:2px}.languages a{font-size:11px;padding:6px 8px}.hero{padding:32px 0}.hero h1{font-size:36px}.hero blockquote{font-size:14px}.hero .lead{font-size:16px}.hero-actions .button{width:100%}.takeaway{grid-template-columns:1fr;gap:12px}.takeaway p{font-size:21px}.takeaway-number{font-size:46px}.toc{gap:8px 16px}.toc a{font-size:12px}.lesson{padding:36px 0 40px}.lesson h2{font-size:26px}.cards,.team{grid-template-columns:1fr}.unit-symbol{font-size:43px}.units .info-card{display:grid;grid-template-columns:60px 1fr;gap:0 12px}.units .info-card h3{margin:0}.units .info-card .meaning{grid-column:2}.units .info-card p:last-child{grid-column:2}.wire-board{grid-template-columns:64px minmax(0,1fr) 64px;gap:10px;padding:22px 12px}.device-box{font-size:12px}.device-box svg{width:40px;height:60px}.wire{font-size:10px}.wire span{padding-inline:0}.wire-paths{gap:23px}.callout{padding:20px}.callout h3{font-size:18px}.calculator{grid-template-columns:1fr 1fr;padding:22px;gap:20px}.calculator .answer{grid-column:1/-1;display:flex;align-items:center;gap:20px;border-left:0;border-top:1px solid var(--line);padding:16px 0 0}.answer strong{font-size:34px}.conversation{gap:18px}.demo-console{padding:23px}.step{padding:18px 14px;gap:10px}.step h3{font-size:16px}.bubble{font-size:15px}.team article:not(:last-child):after{right:calc(50% - 8px);top:auto;bottom:-21px}.glossary{grid-template-columns:1fr}.glossary dt{border-bottom:0;padding-bottom:3px}.glossary dd{padding-top:2px}.next-steps{padding:25px 22px}.next-steps h2{font-size:24px}.faq-list summary{font-size:16px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.demo-enabled .step{transition:none}}
@media print{body{background:white;color:#111;font-size:11pt}.languages,.toc,.hero-actions,.demo-controls,.calculator,.site-footer{display:none}.hero{display:block;padding:10px 0}.hero h1{font-size:28pt}.takeaway{transform:none;box-shadow:none}.lesson{padding:20px 0}.conversation,.cards,.team,.summary-grid{display:block}.demo-console{position:static}.demo-enabled .step{opacity:1}.info-card,.step,.team article,.callout,.next-steps,.takeaway{background:transparent;break-inside:avoid}.step,.info-card{margin-bottom:12px}.faq-list details>*{display:block}.faq-list details{break-inside:avoid}.wrap{width:100%}.lesson>p,.info-card p,.note,.sources,.glossary dd,.callout p{color:#333!important}a{color:#16486b}.next-steps{break-inside:avoid}}
.calculator .answer #power-value{display:block;color:var(--gold);font-size:38px;line-height:1.5;font-weight:750}.demo-console .speaker{margin-top:18px}.demo-console .bubble{font-size:16px}