:root{--ink:#182a31;--muted:#53676e;--accent:#086a68;--line:#dce5e8;--paper:#fff;--wash:#f4f8f9}*{box-sizing:border-box}body{margin:0;color:var(--ink);background:var(--paper);font-family:-apple-system,BlinkMacSystemFont,'PingFang SC','Microsoft YaHei',sans-serif;font-size:16px;line-height:1.8}a{color:var(--accent);text-underline-offset:4px}a:hover{color:#003d40}button,input{font:inherit}button,a,input{touch-action:manipulation}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #e99224;outline-offset:4px}#sidebar{width:250px;background:#112b33;color:#d7e5e9;position:fixed;inset:0 auto 0 0;padding:32px 24px;overflow-y:auto;display:flex;flex-direction:column}.brand{font-weight:700;font-size:19px;color:white;text-decoration:none}.brand-mark{display:block;font-family:Georgia,serif;font-size:54px;line-height:1.3;color:#84d6ce}.brand:hover{color:#fff}.side-note{font-size:14px;color:#9ab8c1;margin:14px 0 30px}nav{display:grid;gap:5px}nav a{padding:9px 12px;color:#d5e2e7;text-decoration:none;border-radius:4px;font-size:15px}nav a:hover,nav a[aria-current]{color:#fff;background:#24434c}.nav-label{font-size:13px;letter-spacing:2px;color:#9ab8c1;margin:30px 12px 10px}.side-bottom{margin-top:auto;padding-top:45px;font-size:13px;color:#9ab8c1}.side-bottom a{color:#9ab8c1}.workspace{margin-left:250px}.topbar{display:flex;justify-content:space-between;gap:16px;padding:18px 5vw;border-bottom:1px solid var(--line);font-size:14px;color:var(--muted)}.topbar a{text-decoration:none}main{max-width:1160px;margin:auto;padding:48px 5vw 72px}h1,h2,h3,p{overflow-wrap:anywhere}h1{font-family:Georgia,'Songti SC',serif;font-size:clamp(30px,3.4vw,48px);line-height:1.35;letter-spacing:-1px;margin:12px 0 20px}h2{font-size:23px;margin:38px 0 16px;line-height:1.5}h3{font-size:19px;line-height:1.5;margin:10px 0}p{margin:16px 0;max-width:850px}.lede{font-size:19px;line-height:1.9;color:var(--muted);max-width:780px}.eyebrow{font-size:13px;letter-spacing:1.3px;color:var(--accent);font-weight:650;text-transform:uppercase}.english{font-family:Georgia,serif;font-size:15px;color:var(--muted)}.meta{font-size:14px;color:var(--muted)}.search-form{display:flex;margin:28px 0;max-width:800px;gap:8px}.search-form input,.filters input{width:100%;min-width:0;border:1px solid #b7c9cd;background:white;padding:13px 17px;border-radius:4px}.search-form button{border:0;background:var(--accent);color:white;padding:12px 25px;border-radius:4px;white-space:nowrap}.stats{display:flex;flex-wrap:wrap;gap:20px 32px;border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:20px 0;margin:32px 0;color:var(--muted);font-size:14px}.stats b{font-family:Georgia,serif;font-size:29px;color:var(--ink);font-weight:400;padding-right:8px}.section-head{display:flex;align-items:baseline;justify-content:space-between;gap:20px;margin:40px 0 18px}.section-head h2{margin:0}.section-head a{font-size:14px;white-space:nowrap}.book-list{border-top:1px solid var(--line)}.book-row{display:flex;gap:24px;align-items:center;text-decoration:none;color:var(--ink);padding:24px 8px;border-bottom:1px solid var(--line);transition:background .15s}.book-row:hover{background:var(--wash)}.book-row p{margin:4px 0;color:var(--muted)}.book-row h3{font-family:'Songti SC',Georgia,serif;font-size:25px;margin:3px 0}.book-num{font-family:Georgia,serif;font-size:35px;align-self:flex-start;color:#80959b;width:54px;flex-shrink:0}.arrow{margin-left:auto;color:var(--accent);font-size:25px}.path-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}.path-card{text-decoration:none;color:var(--ink);border:1px solid var(--line);padding:24px;background:var(--wash)}.path-card h2,.path-card h3{margin:0 0 10px;font-size:19px}.path-card p{font-size:16px;color:var(--muted);margin:8px 0 18px}.path-card span{color:var(--accent);font-size:14px}.concept-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.concept-card{display:block;text-decoration:none;color:var(--ink);padding:22px 20px;border:1px solid var(--line);border-top:3px solid var(--accent);border-radius:3px}.concept-card:hover{background:var(--wash)}.concept-card h3{margin:12px 0}.concept-card p{font-size:16px;color:var(--muted)}.read-more{font-size:14px;color:var(--accent)}.filters{margin:25px 0}.filters>div{display:flex;flex-wrap:wrap;gap:8px;margin-top:16px}.filters button{padding:7px 15px;border:1px solid var(--line);background:#fff;border-radius:3px;font-size:15px}.filters button[aria-pressed=true]{background:var(--ink);color:white;border-color:var(--ink)}.chips{display:flex;flex-wrap:wrap;gap:10px}.chips a{padding:7px 14px;background:var(--wash);border:1px solid var(--line);border-radius:3px;text-decoration:none;font-size:15px}.question{border-left:3px solid var(--accent);background:var(--wash);padding:20px 25px;margin:32px 0}.question p{font-size:19px;margin:8px 0}.sources,.related{list-style:none;padding:0}.sources li,.related li{border-bottom:1px solid var(--line);padding:18px 0}.sources span{display:block;font-size:14px;color:var(--muted)}.related p{margin:8px 0;font-size:16px;color:var(--muted)}.tag{display:inline-block;font-size:13px;margin-left:10px;background:var(--wash);padding:1px 8px;color:var(--muted)}.chapter-list{padding-left:23px}.chapter-list li{padding:9px 0;border-bottom:1px solid var(--line)}.steps{list-style:decimal-leading-zero;padding-left:40px}.steps>li{padding:5px 0 25px 10px;border-bottom:1px solid var(--line)}.steps>li::marker{font-size:24px;color:var(--accent);font-family:Georgia,serif}.steps h2{margin-top:14px}.step-question{color:var(--accent)}.source-entry{border-top:1px solid var(--line);padding:18px 0;scroll-margin-top:20px}.source-entry p{margin:6px 0}.source-entry code{font-size:13px;overflow-wrap:anywhere}.source-book{margin:40px 0}.graph-wrap{border:1px solid var(--line);background:#f8fbfb;overflow:auto;max-width:100%}.graph-wrap svg{display:block;width:100%;min-width:920px}.edge{stroke:#c7d9db;stroke-width:1}.edge.active{stroke:#087c78;stroke-width:2.8}.edge.dim{opacity:.12}.graph-wrap circle{fill:#086a68;stroke:white;stroke-width:3}.graph-wrap text{font-size:15px;fill:var(--ink);font-family:inherit}.graph-wrap a{cursor:pointer}.graph-wrap a.active circle{fill:#cf7625;r:13}.graph-wrap a.dim{opacity:.25}.graph-wrap a:hover text{fill:var(--accent);font-weight:bold}.graph-wrap .group-label{font-size:22px;font-weight:bold;fill:#78949b}.result{border-bottom:1px solid var(--line);padding:22px 0}.result h2{margin:0;font-size:20px}.result p{margin:8px 0}.result small{color:var(--muted);font-size:14px}footer{border-top:1px solid var(--line);padding:30px 5vw;color:var(--muted);font-size:14px}.mobile{display:none}.skip{position:fixed;top:-80px;left:20px;background:white;padding:12px;z-index:10}.skip:focus{top:10px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}[hidden]{display:none!important}@media(max-width:1100px){.concept-grid{grid-template-columns:repeat(2,minmax(0,1fr))}#sidebar{width:220px;padding:26px 18px}.workspace{margin-left:220px}main{padding:35px 4vw 55px}.brand{font-size:17px}}@media(max-width:760px){.mobile{display:flex;align-items:center;justify-content:space-between;padding:14px 20px;background:#112b33;position:sticky;top:0;z-index:5}.mobile a{color:#fff;text-decoration:none;font-weight:bold}.mobile button{background:transparent;color:white;border:1px solid #66848f;padding:4px 12px;border-radius:3px}#sidebar{display:none;inset:58px 0 0;width:100%;z-index:4}body.menu-open #sidebar{display:flex}.workspace{margin-left:0}.topbar{padding:14px 20px;font-size:13px}main{padding:28px 20px 45px}h1{font-size:31px}.lede{font-size:17px}.stats{gap:12px 24px}.stats span{width:calc(50% - 12px)}.stats b{font-size:27px}.book-row{gap:12px;padding:22px 0}.book-num{font-size:26px;width:35px}.book-row h3{font-size:22px}.book-row p{font-size:15px}.book-row .english{font-size:13px}.concept-grid,.path-grid{grid-template-columns:1fr}.section-head{gap:10px}.section-head h2{font-size:21px}.section-head a{font-size:13px}.concept-card{padding:20px}.source-entry code{font-size:12px}.graph-wrap{margin:0}.search-form button{padding:10px 18px}footer{padding:24px 20px}}