:root{--blue:#245b80;--ink:#25343d;--muted:#647580;--line:#cad9e2;--tint:#eff5f8}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:88px}body{margin:0;background:#fafbfc;color:var(--ink);font-family:'Songti SC','STSong','SimSun',serif}a{color:var(--blue);text-underline-offset:4px}.site-header{height:65px;padding:0 5vw;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);background:#fff;font:13px -apple-system,BlinkMacSystemFont,'PingFang SC',sans-serif;letter-spacing:1px}.site-header a{text-decoration:none}.site-header a:first-child{font-weight:700}main{max-width:1260px;margin:auto;padding:0 36px}.book-title{margin-left:234px;padding:65px 50px 42px;background:#fff}.book-kicker{font:16px 'PingFang SC',sans-serif;letter-spacing:3px;color:var(--blue)}h1{font-size:43px;letter-spacing:2px;font-weight:600;line-height:1.4;margin:20px 0 10px}.book-title>p{font-size:18px;color:var(--muted)}.title-rule{width:75px;height:4px;background:var(--blue);margin-top:30px}.layout{display:grid;grid-template-columns:210px minmax(0,1fr);gap:24px}aside{font:13px/1.6 'PingFang SC',sans-serif;position:sticky;top:28px;align-self:start;max-height:calc(100vh - 55px);overflow:auto;padding:10px 0}aside summary{font-size:15px;color:var(--blue);font-weight:600;cursor:pointer;padding:0 8px 12px}nav{display:grid;gap:3px}nav a{padding:8px 10px;display:flex;align-items:baseline;gap:10px;text-decoration:none;color:#526471;border-left:2px solid transparent}nav a span{font-size:11px;color:#8a9da9}nav a:hover,nav a[aria-current=true]{background:#eaf1f6;border-left-color:var(--blue);color:var(--blue)}article{background:white;padding:0 50px 50px;min-width:0}.introduction{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:22px 0;margin-bottom:50px}.introduction>b{font:600 17px 'PingFang SC',sans-serif;color:var(--blue)}article p{font-size:18px;line-height:2;text-align:justify;margin:18px 0;text-indent:2em;overflow-wrap:anywhere}.introduction p{font-size:16px;line-height:1.95;margin-bottom:0}.chapter{padding-top:22px;margin-bottom:58px;scroll-margin-top:20px}.section-label{font:13px 'PingFang SC',sans-serif;color:var(--blue);letter-spacing:2px;margin-bottom:10px}h2{font:600 27px/1.55 'PingFang SC',sans-serif;color:var(--blue);border-bottom:2px solid var(--blue);padding-bottom:15px;margin:0 0 25px}h3{font:600 20px/1.7 'PingFang SC',sans-serif;margin:36px 0 14px;color:var(--blue);border-left:4px solid #91adc1;padding-left:13px}sup{font:11px sans-serif}sup a{text-decoration:none}.diagram{margin:30px 0 35px;padding:24px 0 14px;border-top:1px solid var(--line);border-bottom:1px solid var(--line);break-inside:avoid}.figure-body svg{width:100%;height:auto;display:block;font-family:'PingFang SC',sans-serif}.diagram figcaption{font:14px/1.8 'PingFang SC',sans-serif;text-align:center;color:var(--blue);margin-top:18px}.diagram .figure-note{font:13px/1.85 'PingFang SC',sans-serif;color:var(--muted);text-indent:0;margin:8px 12px 0;text-align:left}.flow{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:28px;font-family:'PingFang SC',sans-serif}.flow-step{position:relative;padding:8px 0}.flow-step:not(:last-child):after{content:'→';position:absolute;right:-23px;top:38px;color:var(--blue);font-size:22px}.flow-step>span{color:#829dad;font:12px sans-serif;display:block;margin-bottom:9px}.flow-step strong{font-size:17px;color:var(--blue);line-height:1.7}.flow-step p{font:15px/1.85 'PingFang SC',sans-serif;text-indent:0;text-align:left;margin:10px 0}.equation{font:500 22px/1.8 'Times New Roman','PingFang SC',sans-serif;text-align:center;padding:18px 12px;background:var(--tint);margin:24px 0;overflow-wrap:anywhere}.formula{font:20px/1.8 'Times New Roman','PingFang SC',sans-serif;text-align:center;padding:15px 4px}.worked{display:grid;grid-template-columns:1fr 1fr;gap:28px;font-family:'PingFang SC',sans-serif}.worked>div+div{border-left:1px solid var(--line);padding-left:24px}.worked h4{font-size:16px;color:var(--blue);margin:0 0 18px}.worked p{font:15px/1.85 'PingFang SC',sans-serif;text-indent:0;text-align:left}.worked b{font-size:15px}.charge-bar{display:flex;background:#d6bb8d;height:40px;align-items:center;font-size:12px;color:#fff}.charge-bar span{background:var(--blue);width:90%;height:100%;display:grid;place-items:center}.charge-bar i{font-size:10px;font-style:normal;color:#453b2b}.voltage span{display:block;background:#527f9b;width:var(--w);font-size:12px;color:white;padding:5px 8px;margin:7px 0}.voltage span+span{background:#91afc2}table{border-collapse:collapse;width:100%;font:15px/1.8 'PingFang SC',sans-serif;margin:10px 0}th,td{text-align:center;padding:10px;border-bottom:1px solid var(--line)}thead{background:var(--tint)}.reference{font-size:15px;line-height:1.9;text-indent:0;scroll-margin-top:30px}footer{border-top:1px solid var(--line);padding:25px 0;color:var(--muted);font:13px/1.9 'PingFang SC',sans-serif}footer a{display:block;margin-top:15px}.back-top{position:fixed;right:15px;bottom:20px;background:white;border:1px solid var(--line);padding:10px;font:12px sans-serif;text-decoration:none}@media(max-width:950px){main{padding:0 20px}.layout{grid-template-columns:165px minmax(0,1fr);gap:15px}.book-title{margin-left:180px;padding:40px 28px}article{padding:0 28px 35px}.flow{gap:20px}.flow-step:not(:last-child):after{right:-18px}h1{font-size:34px}article p{font-size:17px}}@media(max-width:700px){html{scroll-padding-top:15px}main{padding:0}.site-header{padding:0 20px;font-size:11px}.book-title{margin:0;padding:36px 24px 24px}h1{font-size:30px}.book-kicker{font-size:13px}.book-title>p{font-size:15px}.layout{display:block}aside{position:relative;top:auto;max-height:none;margin:0 24px 20px;padding:10px 0;background:#eff5f8}aside summary{padding-left:14px}nav{grid-template-columns:1fr 1fr;padding:0 6px}nav a{font-size:12px;padding:6px}article{padding:0 24px 30px}h2{font-size:23px}article p{font-size:17px;line-height:1.95}.flow{grid-template-columns:1fr;gap:24px}.flow-step{padding:0 0 0 28px}.flow-step>span{position:absolute;left:0;top:5px}.flow-step:not(:last-child):after{content:'↓';left:4px;right:auto;top:auto;bottom:-24px;font-size:20px}.flow-step p{margin:5px 0}.worked{grid-template-columns:1fr;gap:24px}.worked>div+div{border-left:0;border-top:1px solid var(--line);padding:20px 0 0}.equation{font-size:18px}.diagram{margin:25px -5px}.figure-body:has(svg){overflow-x:auto}.figure-body svg{min-width:580px}.back-top{right:8px;bottom:8px}.chapter{margin-bottom:40px}.introduction{margin-bottom:25px}}@media print{body{background:white}.site-header,aside,.back-top{display:none}.layout{display:block}main{max-width:none;padding:0}.book-title{margin:0}article{padding:0 30px}.chapter{break-before:page}.diagram{break-inside:avoid}a{color:inherit}}
@media(max-width:700px){.diagram:has(svg) figcaption:after{content:'（图可左右滑动）';font-size:11px;display:block;color:var(--muted)}}