/* ============ AI Systems Performance Engineering · 中文版 ============ */
:root{
  --bg:#fbfaf7;--bg-soft:#f4f2ec;--panel:#fff;--ink:#1c1b19;--ink-2:#4a4741;--ink-3:#7b756b;
  --line:#e3ded2;--line-2:#d3ccbc;--accent:#0f5f6b;--accent-2:#0d7482;--accent-soft:#e6f1f2;
  --code-bg:#1e2530;--code-ink:#e8eef5;--note:#2f6fa8;--tip:#2f7d4f;--warn:#a8641b;--danger:#a33a3a;
  --serif:"Noto Serif SC","Source Han Serif SC","Songti SC","STSong","SimSun",Georgia,serif;
  --kai:"Kaiti SC","STKaiti","KaiTi","TW-Kai","Noto Serif SC","Songti SC","SimSun",serif;
  --read:var(--serif);
  --sans:"Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --mono:"JetBrains Mono","SF Mono",ui-monospace,Menlo,Consolas,"Liberation Mono",monospace;
  --fs:17px;--sidebar:312px;--measure:47rem;
}
html[data-font="song"]{--read:var(--serif)}
html[data-font="hei"]{--read:var(--sans)}
html[data-font="kai"]{--read:var(--kai)}
html[data-font="sys"]{--read:system-ui,-apple-system,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",sans-serif}
html[data-theme="dark"]{
  --bg:#14161a;--bg-soft:#1a1d22;--panel:#1d2026;--ink:#e9e6df;--ink-2:#c2bdb3;--ink-3:#8f897d;
  --line:#2c3037;--line-2:#3a3f47;--accent:#5fc6d4;--accent-2:#7ad4df;--accent-soft:#1c2b30;
  --code-bg:#10141a;--code-ink:#e8eef5;--note:#6aa8dd;--tip:#69c08c;--warn:#d9a45e;--danger:#e08a8a;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--read);font-size:var(--fs);
  line-height:1.86;-webkit-font-smoothing:antialiased}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
code,kbd,samp{font-family:var(--mono);font-size:.86em}
:not(pre)>code{background:var(--accent-soft);color:var(--accent-2);padding:.08em .36em;border-radius:4px;
  border:1px solid rgba(15,95,107,.16);white-space:nowrap}
.layout{display:flex;min-height:100vh}
.sidebar{width:var(--sidebar);flex:0 0 var(--sidebar);position:sticky;top:0;height:100vh;overflow-y:auto;
  background:var(--bg-soft);border-right:1px solid var(--line);padding:26px 20px 40px;font-family:var(--sans);scrollbar-width:thin}
.sidebar::-webkit-scrollbar{width:8px}
.sidebar::-webkit-scrollbar-thumb{background:var(--line-2);border-radius:4px}
.brand{padding:0 4px 18px;border-bottom:1px solid var(--line);margin-bottom:16px}
.brand-title{display:block;font-size:1.24rem;font-weight:700;color:var(--ink);line-height:1.35}
.brand-sub{font-size:.72rem;color:var(--ink-3);letter-spacing:.06em;text-transform:uppercase;margin-top:4px}
.searchbox{position:relative;margin-bottom:16px}
#q{width:100%;padding:9px 12px;font-family:var(--sans);font-size:.86rem;color:var(--ink);
  background:var(--panel);border:1px solid var(--line-2);border-radius:7px;outline:none}
#q:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(15,95,107,.15)}
.results{position:absolute;left:0;right:0;top:calc(100% + 6px);z-index:40;background:var(--panel);
  border:1px solid var(--line-2);border-radius:9px;box-shadow:0 16px 40px rgba(0,0,0,.16);
  max-height:60vh;overflow-y:auto;display:none;font-size:.82rem}
.results.open{display:block}
.results .hit{display:block;padding:9px 12px;border-bottom:1px solid var(--line);color:var(--ink-2)}
.results .hit:last-child{border-bottom:none}
.results .hit:hover{background:var(--accent-soft);text-decoration:none}
.results .hit b{color:var(--accent);font-weight:600}
.results .hit .ctx{display:block;color:var(--ink-3);font-size:.74rem;margin-bottom:2px}
.results .empty{padding:12px;color:var(--ink-3)}
.toc{font-size:.88rem}
.chapters{list-style:none;margin:0;padding:0}
.chapters>li{margin:1px 0}
.chapters>li>a{display:block;padding:6px 10px;border-radius:6px;color:var(--ink-2);line-height:1.5}
.chapters>li>a:hover{background:rgba(15,95,107,.08);color:var(--accent);text-decoration:none}
.chapters>li.current>a{background:var(--accent);color:#fff;font-weight:600}
html[data-theme="dark"] .chapters>li.current>a{color:#0d1416}
.sections{margin:4px 0 8px 10px;padding:0 0 0 10px;border-left:1px solid var(--line-2);list-style:none}
.sections a{display:block;padding:3px 6px;font-size:.79rem;color:var(--ink-3);border-radius:5px;line-height:1.5}
.sections a:hover{color:var(--accent);background:rgba(15,95,107,.07);text-decoration:none}
.pdflink{display:inline-block;margin-top:6px;padding:4px 9px;border:1px solid var(--line-2);
  border-radius:6px;color:var(--accent);font-weight:600;text-decoration:none}
.pdflink:hover{background:var(--accent-soft)}
.totop{position:fixed;right:22px;bottom:26px;z-index:40;width:40px;height:40px;border-radius:50%;
  border:1px solid var(--line-2);background:var(--bg-2);color:var(--ink-2);font-size:18px;cursor:pointer;
  opacity:0;pointer-events:none;transition:opacity .2s ease,transform .2s ease;box-shadow:0 4px 18px rgba(0,0,0,.12)}
.totop.show{opacity:1;pointer-events:auto}
.totop:hover{transform:translateY(-2px)}
@media print{.totop{display:none!important}}
.sidebar-foot{margin-top:22px;padding-top:14px;border-top:1px solid var(--line);font-size:.7rem;color:var(--ink-3);line-height:1.7}
.main{flex:1;min-width:0;display:flex;flex-direction:column}
.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:10px 30px;background:rgba(251,250,247,.88);backdrop-filter:blur(10px);border-bottom:1px solid var(--line);font-family:var(--sans)}
html[data-theme="dark"] .topbar{background:rgba(20,22,26,.88)}
.crumb{font-size:.82rem;color:var(--ink-3);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.controls{display:flex;gap:6px;flex:0 0 auto}
.controls button{font-family:var(--sans);font-size:.78rem;color:var(--ink-2);background:var(--panel);
  border:1px solid var(--line-2);border-radius:6px;padding:5px 10px;cursor:pointer;transition:.15s}
.controls button:hover{border-color:var(--accent);color:var(--accent)}
.controls button.active{background:var(--accent);border-color:var(--accent);color:#fff}
.controls .fontsel{font-family:var(--sans);font-size:.78rem;color:var(--ink-2);background:var(--panel);
  border:1px solid var(--line-2);border-radius:6px;padding:5px 4px;cursor:pointer;height:29px;
  transition:.15s;-webkit-appearance:none;appearance:none;text-align:center;padding-right:16px;
  background-image:linear-gradient(45deg,transparent 50%,var(--ink-3) 50%),
    linear-gradient(135deg,var(--ink-3) 50%,transparent 50%);
  background-position:calc(100% - 9px) 12px,calc(100% - 5px) 12px;
  background-size:4px 4px,4px 4px;background-repeat:no-repeat}
.controls .fontsel:hover,.controls .fontsel:focus{border-color:var(--accent);color:var(--accent);outline:none}
html[data-theme="dark"] .controls button.active{color:#0d1416}
.toc-btn{display:none;font-family:var(--sans);font-size:.8rem;color:var(--ink);background:var(--panel);
  border:1px solid var(--line-2);border-radius:7px;padding:6px 11px;cursor:pointer;white-space:nowrap}
.toc-btn:hover{border-color:var(--accent);color:var(--accent)}
.rail{width:252px;flex:0 0 252px;position:sticky;top:0;height:100vh;overflow-y:auto;padding:26px 18px 40px;
  border-left:1px solid var(--line);background:var(--bg-soft);font-family:var(--sans);font-size:.8rem;
  scrollbar-width:thin}
.rail-title{font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;color:var(--ink-3);
  padding-bottom:8px;margin-bottom:10px;border-bottom:1px solid var(--line)}
.rail-list{list-style:none;margin:0;padding:0;line-height:1.45}
.rail-list li{margin:1px 0}
.rail-list a{display:block;padding:4px 8px;border-radius:5px;color:var(--ink-2);border-left:2px solid transparent}
.rail-list a:hover{background:rgba(15,95,107,.08);color:var(--accent);text-decoration:none}
.rail-list .lvl3 a{padding-left:20px;font-size:.76rem;color:var(--ink-3)}
.rail-list li.active>a{color:var(--accent);border-left-color:var(--accent);background:rgba(15,95,107,.08);font-weight:600}
.chapter-toc{margin:0 0 2em;border:1px solid var(--line);border-radius:9px;background:var(--bg-soft);
  font-family:var(--sans);font-size:.86rem}
.chapter-toc>summary{cursor:pointer;padding:10px 16px;font-weight:600;color:var(--ink);list-style:none}
.chapter-toc>summary::-webkit-details-marker{display:none}
.chapter-toc>summary::before{content:"▸";display:inline-block;margin-right:.5em;color:var(--accent);transition:transform .15s}
.chapter-toc[open]>summary::before{transform:rotate(90deg)}
.chapter-toc ol{margin:0;padding:2px 20px 14px 34px;color:var(--ink-2);line-height:1.7}
.chapter-toc li{margin:2px 0}
.chapter-toc li.lvl3{list-style:circle;margin-left:1em;font-size:.94em;color:var(--ink-3)}
.menu-btn{display:none;position:fixed;left:14px;bottom:16px;z-index:60;width:44px;height:44px;border-radius:50%;
  border:1px solid var(--line-2);background:var(--panel);color:var(--ink);font-size:1.1rem;cursor:pointer;
  box-shadow:0 6px 20px rgba(0,0,0,.18)}
.progress{position:fixed;top:0;left:0;height:2px;background:var(--accent);width:0;z-index:70;transition:width .1s linear}
.chapter,.landing{width:100%;max-width:var(--measure);margin:0 auto;padding:44px 32px 80px}
.chapter-head{margin-bottom:34px;padding-bottom:22px;border-bottom:1px solid var(--line)}
.chapter-kicker{font-family:var(--sans);font-size:.78rem;letter-spacing:.16em;color:var(--accent);text-transform:uppercase;margin-bottom:10px}
.chapter-head h1{font-family:var(--sans);font-size:2rem;line-height:1.32;margin:0 0 10px}
.chapter-title-en{font-family:var(--sans);font-size:.88rem;color:var(--ink-3);margin:0}
.chapter-meta{font-family:var(--sans);font-size:.76rem;color:var(--ink-3);margin-top:12px}
.chapter h2{font-family:var(--sans);font-size:1.42rem;line-height:1.4;margin:2.6em 0 .7em}
.chapter h2::before{content:"";display:block;width:42px;height:3px;background:var(--accent);border-radius:2px;margin-bottom:14px}
.chapter h3{font-family:var(--sans);font-size:1.14rem;line-height:1.5;margin:2em 0 .6em}
.chapter h4{font-family:var(--sans);font-size:1rem;line-height:1.5;margin:1.7em 0 .5em;color:var(--ink-2)}
.chapter p{margin:0 0 1.05em;text-align:justify}
.chapter .heading-en{font-family:var(--sans);font-size:.76rem;color:var(--ink-3);margin:-.3em 0 1.1em}
.lead{font-weight:600;margin-top:1.4em!important}
p.li{margin-left:1.4em;position:relative}
p.li::before{content:"•";position:absolute;left:-1.05em;color:var(--accent)}
.deflist{margin:1.2em 0 1.6em;padding:0}
.deflist dt{font-weight:700;font-family:var(--sans);font-size:.98rem;margin-top:1.15em;color:var(--ink)}
.deflist dt::before{content:"▍";color:var(--accent);margin-right:.4em}
.deflist dd{margin:.35em 0 0 1.15em;color:var(--ink-2);text-align:justify}
blockquote.pull{margin:1.6em 0;padding:14px 20px;border-left:3px solid var(--accent);
  background:rgba(15,95,107,.06);color:var(--ink-2);font-style:italic;border-radius:0 6px 6px 0}
blockquote.pull p{margin:0}
.callout{display:grid;grid-template-columns:84px 1fr;margin:1.6em 0;border:1px solid var(--line-2);
  border-left:4px solid var(--note);border-radius:8px;background:rgba(47,111,168,.06);overflow:hidden}
.callout-label{font-family:var(--sans);font-size:.76rem;font-weight:700;letter-spacing:.08em;color:#fff;
  background:var(--note);display:flex;align-items:center;justify-content:center;padding:10px 6px}
.callout-body{padding:12px 16px}
.callout-body p{margin:0;font-size:.94em}
.callout.tip{border-left-color:var(--tip);background:rgba(47,125,79,.06)}
.callout.tip .callout-label{background:var(--tip)}
.callout.warning,.callout.caution{border-left-color:var(--warn);background:rgba(168,100,27,.08)}
.callout.warning .callout-label,.callout.caution .callout-label{background:var(--warn)}
.callout.important{border-left-color:var(--danger);background:rgba(163,58,58,.06)}
.callout.important .callout-label{background:var(--danger)}
.codeblock{margin:1.5em 0;border-radius:9px;overflow:hidden;border:1px solid var(--line-2);background:var(--code-bg)}
.codehead{display:flex;align-items:center;justify-content:space-between;padding:7px 12px;
  background:rgba(255,255,255,.06);border-bottom:1px solid rgba(255,255,255,.08);font-family:var(--sans)}
.codelang{font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:#9fb0c4}
.copybtn{font-family:var(--sans);font-size:.7rem;color:#c8d4e2;background:transparent;border:1px solid rgba(255,255,255,.22);
  border-radius:5px;padding:2px 8px;cursor:pointer}
.copybtn:hover{background:rgba(255,255,255,.12)}
pre.code-body{margin:0;padding:14px 16px;overflow-x:auto;background:var(--code-bg);color:var(--code-ink);
  font-family:var(--mono);font-size:.8rem;line-height:1.62;tab-size:4}
.code-en{display:none}
body.bilingual .code-en{display:block;border-top:1px dashed rgba(255,255,255,.18)}
body.bilingual .code-en::before{content:"原代码";display:block;font-family:var(--sans);font-size:.66rem;
  letter-spacing:.12em;color:#8fa2b8;margin-bottom:6px}
pre.code-body code{background:none;border:none;padding:0;color:inherit;white-space:pre}
.figure{margin:2em 0;text-align:center}
.figure img{max-width:100%;height:auto;border:1px solid var(--line);border-radius:8px;background:#fff;padding:6px}
.figure figcaption,.tablewrap figcaption{font-family:var(--sans);font-size:.8rem;color:var(--ink-3);margin-top:10px;line-height:1.6;text-align:left}
.fignum{display:inline-block;font-weight:700;color:var(--accent);margin-right:.5em}
.tablewrap{margin:2em 0}
.tablescroll{overflow-x:auto;border:1px solid var(--line-2);border-radius:8px;margin-top:8px}
table{border-collapse:collapse;width:100%;font-family:var(--sans);font-size:.84rem;line-height:1.55}
thead th{background:var(--bg-soft);color:var(--ink);text-align:left;font-weight:600;padding:9px 12px;
  border-bottom:2px solid var(--line-2);white-space:nowrap}
tbody td{padding:8px 12px;border-bottom:1px solid var(--line);color:var(--ink-2);vertical-align:top}
tbody tr:last-child td{border-bottom:none}
tbody tr:nth-child(even){background:rgba(244,242,236,.55)}
html[data-theme="dark"] tbody tr:nth-child(even){background:rgba(255,255,255,.03)}
.pager{max-width:var(--measure);margin:0 auto;padding:0 32px 40px;display:flex;justify-content:space-between;gap:16px;font-family:var(--sans);font-size:.86rem}
.pager a{display:block;flex:1;padding:14px 16px;border:1px solid var(--line-2);border-radius:9px;background:var(--panel);color:var(--ink-2)}
.pager a:hover{border-color:var(--accent);color:var(--accent);text-decoration:none}
.pager .dir{display:block;font-size:.7rem;letter-spacing:.1em;color:var(--ink-3);text-transform:uppercase;margin-bottom:3px}
.pager .next{text-align:right}
.idx-page{max-width:74rem}
.idx-lead{font-family:var(--sans);font-size:.84rem;color:var(--ink-2);background:var(--bg-soft);
  border:1px solid var(--line);border-radius:8px;padding:12px 16px;margin:1.2em 0 1.8em;line-height:1.75}
.idx-entries{columns:3;column-gap:28px;font-size:.8rem;line-height:1.5;color:var(--ink-2)}
.idx-entries .e{break-inside:avoid;margin:0 0 .3em;padding-left:1.1em;text-indent:-1.1em}
.idx-entries .ph{break-inside:avoid;font-family:var(--sans);font-size:.7rem;letter-spacing:.1em;
  color:var(--accent);border-bottom:1px solid var(--line);margin:.6em 0 .5em;padding-bottom:2px}
@media (max-width:1200px){.idx-entries{columns:2}}
@media (max-width:760px){.idx-entries{columns:1}}
.term-table{width:100%;font-size:.86rem}
.term-table td:first-child{font-family:var(--mono);font-size:.82rem;color:var(--ink);white-space:nowrap}
.foot{max-width:var(--measure);margin:0 auto;padding:0 32px 60px;font-family:var(--sans);font-size:.74rem;color:var(--ink-3)}
.cover{padding:26px 0 34px;border-bottom:1px solid var(--line);margin-bottom:28px}
.cover-kicker{font-family:var(--sans);font-size:.76rem;letter-spacing:.18em;text-transform:uppercase;color:var(--accent)}
.cover h1{font-family:var(--sans);font-size:2.7rem;line-height:1.2;margin:.3em 0 .2em}
.cover-sub{font-size:1.05rem;color:var(--ink-2);margin:.2em 0}
.cover-en{font-family:var(--sans);font-size:.86rem;color:var(--ink-3);margin:.6em 0 1.2em}
.cover-meta{display:flex;flex-wrap:wrap;gap:8px 18px;font-family:var(--sans);font-size:.8rem;color:var(--ink-3)}
.intro h2,.tocpage h2{font-family:var(--sans);font-size:1.25rem;margin:1.6em 0 .6em}
.intro ul{padding-left:1.2em;color:var(--ink-2)}
.intro li{margin:.4em 0}
.applinks{list-style:none;padding:0;font-family:var(--sans);font-size:.9rem}
.applinks li{padding:8px 0;border-bottom:1px dashed var(--line);color:var(--ink-3)}
.applinks a{font-weight:600;margin-right:.6em}
.toclist{list-style:none;padding:0;font-family:var(--sans)}
.toclist>li{margin:.2em 0;padding:8px 0;border-bottom:1px dashed var(--line)}
.toclist>li>a{font-weight:600;color:var(--ink);font-size:1rem}
.toclist>li>a:hover{color:var(--accent);text-decoration:none}
.toclist ul{list-style:none;padding:6px 0 0 14px;margin:0;display:grid;grid-template-columns:1fr 1fr;gap:2px 18px}
.toclist ul a{font-size:.8rem;color:var(--ink-3);font-weight:400}
.en{display:none}
body.bilingual .en{display:block}
body.bilingual .en{display:block;margin:0 0 .32em;padding:0;border:0;font-family:var(--sans);
  font-size:.86em;line-height:1.66;color:var(--ink-2);font-weight:400;font-style:normal;text-align:left}
body.bilingual td .en,body.bilingual th .en{font-size:.9em;line-height:1.5;margin:0 0 .18em}
body.bilingual blockquote.pull .en{margin:0 0 .45em}
body.bilingual .callout-body .en{margin:0 0 .35em}
body.bilingual figcaption .en{margin:.28em 0 0;font-size:.86em;color:var(--ink-3)}
body.bilingual .heading-en{display:block;margin:-.45em 0 1.05em;padding:0;border:0;
  font-size:.82rem;line-height:1.5;color:var(--ink-3);font-family:var(--sans)}
body:not(.bilingual) .heading-en{display:none}
body.bilingual p.li::before,body.bilingual .deflist dt::before{opacity:.75}
@media (max-width:1280px){.rail{display:none}}
@media (max-width:1080px){:root{--sidebar:280px}.chapter,.landing{padding:34px 24px 70px}}
@media (max-width:900px){
  .toc-btn{display:block}
  .sidebar{position:fixed;left:0;top:0;z-index:50;transform:translateX(-100%);transition:transform .25s ease;box-shadow:0 0 40px rgba(0,0,0,.25)}
  body.nav-open .sidebar{transform:none}
  .menu-btn{display:block}
  .topbar{padding:10px 16px;gap:8px}
  .crumb{flex:1}
  .chapter,.landing{padding:24px 18px 64px}
  .chapter-head h1{font-size:1.55rem}
  .cover h1{font-size:2rem}
  .toclist ul{grid-template-columns:1fr}
  .callout{grid-template-columns:1fr}
  .callout-label{justify-content:flex-start;padding:6px 14px}
}
@media print{
  .sidebar,.topbar,.pager,.menu-btn,.progress,.copybtn{display:none!important}
  .chapter{max-width:none;padding:0}
  .codeblock,.figure,.tablewrap{break-inside:avoid}
}