:root{--bg:#f7f6f2;--surface:#fff;--text:#182431;--muted:#66717c;--line:#dfe3e3;--accent:#176b6b;--accent-soft:#e4f1ef;--gold:#b97a20;--code:#17242b;--shadow:0 16px 48px rgba(27,42,50,.12);color-scheme:light}
[data-theme="dark"]{--bg:#101719;--surface:#172124;--text:#e8eeee;--muted:#9aa9aa;--line:#2b3a3d;--accent:#72c6bb;--accent-soft:#1d3736;--gold:#e5ae5b;--code:#0b1113;--shadow:0 18px 54px rgba(0,0,0,.28);color-scheme:dark}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:88px}body{margin:0;background:var(--bg);color:var(--text);font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;line-height:1.75}.topbar{position:fixed;z-index:50;inset:0 0 auto 0;height:64px;display:flex;align-items:center;justify-content:space-between;padding:0 24px;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:10px;color:var(--text);font-weight:700;text-decoration:none}.brand-mark{display:grid;place-items:center;width:32px;height:32px;border-radius:9px;background:var(--accent);color:var(--surface);font-family:Georgia,serif;font-size:13px}.icon-button,.close-button{border:0;background:transparent;color:var(--text);font-size:22px;cursor:pointer;padding:8px}.menu-button,.close-button{display:none}.shell{display:grid;grid-template-columns:288px minmax(0,1fr);max-width:1440px;margin:auto;padding-top:64px}.sidebar{position:sticky;top:64px;height:calc(100vh - 64px);padding:28px 20px;border-right:1px solid var(--line);overflow:auto}.sidebar-head{display:flex;justify-content:space-between;align-items:center;margin:0 8px 14px;color:var(--muted);font-size:12px;font-weight:800;letter-spacing:.14em}.search{display:flex;align-items:center;gap:8px;padding:9px 12px;margin-bottom:20px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--muted)}.search:focus-within{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}.search input{min-width:0;width:100%;border:0;outline:0;background:transparent;color:var(--text);font:inherit;font-size:14px}.toc-chapter{margin:20px 8px 7px;color:var(--text);font-size:13px;font-weight:800}.toc-link{display:block;padding:7px 9px;border-left:2px solid transparent;border-radius:0 7px 7px 0;color:var(--muted);font-size:13px;line-height:1.45;text-decoration:none}.toc-link:hover,.toc-link.active{border-left-color:var(--accent);background:var(--accent-soft);color:var(--accent)}.content{width:min(100%,900px);padding:56px 64px 80px}.hero{padding:30px 0 54px;border-bottom:1px solid var(--line)}.eyebrow{margin-bottom:14px;color:var(--gold);font-size:12px;font-weight:800;letter-spacing:.18em}.hero h1{max-width:680px;margin:0;font-family:Georgia,"Songti SC",serif;font-size:clamp(38px,6vw,66px);line-height:1.08;letter-spacing:-.04em}.hero p{max-width:620px;margin:22px 0 24px;color:var(--muted);font-size:17px}.stats{display:flex;gap:12px;flex-wrap:wrap}.stats span{padding:7px 12px;border:1px solid var(--line);border-radius:999px;color:var(--muted);font-size:13px}.stats strong{color:var(--accent)}.document{padding-top:24px}.document h1{margin:72px 0 26px;padding-top:14px;border-top:3px solid var(--text);font-family:Georgia,"Songti SC",serif;font-size:34px;line-height:1.25}.document h2{margin:52px 0 18px;font-size:24px;line-height:1.4}.document h3{margin:30px 0 10px;color:var(--accent);font-size:16px}.document p{margin:10px 0}.question{display:contents}.answer-callout{margin:18px 0;padding:16px 18px;border-left:3px solid var(--accent);border-radius:0 9px 9px 0;background:var(--accent-soft);font-weight:600}.bullet{padding-left:22px;position:relative}.bullet:before{content:"";position:absolute;left:5px;top:.8em;width:6px;height:6px;border-radius:50%;background:var(--gold)}.code-block{position:relative;margin:18px 0;padding:20px;overflow:auto;border-radius:12px;background:var(--code);color:#dce8e7;font:13px/1.65 "SFMono-Regular",Consolas,monospace;box-shadow:var(--shadow)}.copy-button{position:absolute;top:9px;right:9px;padding:5px 8px;border:1px solid #44555a;border-radius:6px;background:#223238;color:#cdd8d8;cursor:pointer}.table-wrap{overflow:auto;margin:20px 0;border:1px solid var(--line);border-radius:10px}table{width:100%;border-collapse:collapse;font-size:14px}th,td{padding:12px 14px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top}th{background:var(--accent);color:var(--surface)}tr:last-child td{border-bottom:0}tr:nth-child(odd) td{background:color-mix(in srgb,var(--surface) 55%,transparent)}.search-status{display:none;margin:26px 0;padding:12px 14px;border-radius:9px;background:var(--accent-soft);color:var(--accent)}mark{padding:1px 2px;border-radius:3px;background:#ffe08a;color:#202020}.is-hidden{display:none!important}.loading,footer{color:var(--muted)}footer{margin-top:72px;padding-top:20px;border-top:1px solid var(--line);font-size:12px}.back-top{position:fixed;right:22px;bottom:22px;width:42px;height:42px;border:0;border-radius:50%;background:var(--text);color:var(--bg);box-shadow:var(--shadow);cursor:pointer;opacity:0;transform:translateY(10px);pointer-events:none;transition:.2s}.back-top.visible{opacity:1;transform:none;pointer-events:auto}.scrim{display:none}
@media(max-width:800px){.topbar{padding:0 12px}.menu-button,.close-button{display:block}.brand{font-size:14px}.shell{display:block}.sidebar{position:fixed;z-index:70;top:0;left:0;width:min(86vw,320px);height:100vh;background:var(--bg);box-shadow:var(--shadow);transform:translateX(-105%);transition:transform .24s ease}.sidebar.open{transform:none}.scrim{position:fixed;z-index:60;inset:0;display:block;background:rgba(5,13,15,.45);opacity:0;pointer-events:none;transition:opacity .24s}.scrim.open{opacity:1;pointer-events:auto}.content{padding:34px 20px 64px}.hero{padding-top:16px}.hero h1{font-size:42px}.document h1{font-size:29px}.document h2{font-size:21px;margin-top:42px}.answer-callout{margin-left:-5px;margin-right:-5px}.code-block{margin-left:-8px;margin-right:-8px;border-radius:9px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition:none!important}}
@media(min-width:801px){.shell{grid-template-columns:320px minmax(0,1fr);max-width:none;margin:0;width:100%}.sidebar{padding-left:24px;padding-right:24px}.content{justify-self:center;width:min(100%,1028px)}.toc-chapter{margin-top:24px;margin-bottom:9px;font-size:16px;line-height:1.4}}
.toc-group{margin:7px 0}.toc-toggle{display:grid;grid-template-columns:30px 1fr 18px;gap:9px;align-items:center;width:100%;padding:10px 8px;border:0;border-radius:9px;background:transparent;color:var(--text);font:inherit;font-size:15px;font-weight:800;text-align:left;cursor:pointer}.toc-toggle:hover{background:var(--accent-soft)}.toc-symbol{display:grid;place-items:center;width:28px;height:28px;border-radius:8px;background:var(--accent-soft);color:var(--accent);font:700 10px/1 monospace}.toc-chevron{color:var(--muted);font-size:17px;transition:transform .2s}.toc-group.open .toc-chevron{transform:rotate(180deg)}.toc-children{display:none;margin-left:17px;padding-left:12px;border-left:1px solid var(--line)}.toc-group.open .toc-children{display:block}.toc-link{position:relative;padding-left:13px}.toc-link:before{content:"";position:absolute;left:-15px;top:14px;width:5px;height:5px;border-radius:50%;background:var(--line)}.toc-link.active:before{background:var(--accent);box-shadow:0 0 0 4px var(--accent-soft)}
.question{display:block;margin:22px 0 50px;padding-bottom:14px;border-bottom:1px dashed var(--line)}.document .question h2{display:flex;gap:14px;align-items:flex-start;margin:0 0 22px;padding:18px 20px;border:1px solid var(--line);border-radius:14px;background:var(--surface);box-shadow:0 8px 28px rgba(27,42,50,.06);font-size:23px}.question-number{display:grid;flex:0 0 38px;place-items:center;width:38px;height:38px;margin-top:-2px;border-radius:11px;background:var(--text);color:var(--bg);font:800 15px/1 monospace}.guide-icon{display:grid;flex:0 0 36px;place-items:center;width:36px;height:36px;border-radius:50%;background:var(--accent-soft);color:var(--accent);font-size:12px}.answer-text{color:var(--text)}.key-point{position:relative;padding-left:28px}.key-point:before{content:"✓";position:absolute;left:0;top:2px;display:grid;place-items:center;width:19px;height:19px;border-radius:50%;background:var(--accent-soft);color:var(--accent);font-size:11px;font-weight:900}.mistake{margin:20px 0!important;padding:14px 16px 14px 45px;border:1px solid color-mix(in srgb,var(--gold) 35%,var(--line));border-radius:10px;background:color-mix(in srgb,var(--gold) 9%,var(--surface));position:relative}.mistake:before{content:"!";position:absolute;left:15px;top:15px;display:grid;place-items:center;width:20px;height:20px;border-radius:50%;background:var(--gold);color:white;font-weight:900}.follow-up{margin:18px 0 0!important;padding:12px 16px 12px 44px;border-radius:10px 10px 0 0;background:var(--accent-soft);color:var(--accent);font-weight:750;position:relative}.follow-up:before{content:"?";position:absolute;left:15px;top:13px;display:grid;place-items:center;width:20px;height:20px;border:2px solid var(--accent);border-radius:50%;font-weight:900;line-height:1}.reference-answer{margin:0 0 16px!important;padding:14px 16px 16px 44px;border:1px solid var(--line);border-top:0;border-radius:0 0 10px 10px;background:var(--surface);color:var(--muted);position:relative}.reference-answer:before{content:"A";position:absolute;left:17px;top:15px;color:var(--accent);font:800 13px/1 monospace}.inline-code{padding:2px 5px;border-radius:5px;background:var(--accent-soft);color:var(--accent);font:90%/1.4 "SFMono-Regular",Consolas,monospace}.table-wrap{box-shadow:0 10px 30px rgba(27,42,50,.07)}
@media(max-width:800px){.document .question h2{padding:15px;font-size:20px}.question-number{flex-basis:34px;width:34px;height:34px}.question{margin-bottom:38px}}
.toc-toggle{list-style:none}.toc-toggle::-webkit-details-marker{display:none}.toc-group[open] .toc-chevron{transform:rotate(180deg)}.toc-group[open] .toc-children{display:block}
.toc-chevron{place-self:center;width:9px;height:9px;border-right:2px solid var(--muted);border-bottom:2px solid var(--muted);font-size:0;transform:rotate(45deg);transform-origin:center;transition:transform .2s}.toc-group[open] .toc-chevron{transform:rotate(225deg)}
.toc-toggle{border:1px solid transparent;transition:background-color .18s,border-color .18s,box-shadow .18s,color .18s}.toc-toggle:hover{border-color:var(--line);background:var(--surface);color:var(--accent);box-shadow:0 6px 18px rgba(27,42,50,.08)}.toc-group[open] .toc-children{margin-top:8px}.toc-link{margin:4px 0;border:1px solid transparent;border-left-width:2px;border-radius:8px;transition:background-color .16s,border-color .16s,color .16s,transform .16s}.toc-link:hover{border-color:color-mix(in srgb,var(--accent) 24%,var(--line));background:color-mix(in srgb,var(--accent-soft) 58%,transparent);color:var(--accent);transform:translateX(2px)}.toc-link.active{border-color:var(--accent);background:var(--accent);color:#fff}.toc-link.active:before{background:var(--accent);box-shadow:0 0 0 4px var(--bg)}