@charset "UTF-8";
:root{--paper:#f7f5ef;--white:#fffefa;--ink:#243f36;--text:#29332e;--muted:#66736b;--line:#dcded4;--soft:#e9eee5;--accent:#bd573b;--serif:"Iowan Old Style","Songti SC","STSong",serif;--sans:"Avenir Next","PingFang SC","Microsoft YaHei",sans-serif;--reader:18px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:0}body{margin:0;background:var(--paper);color:var(--text);font-family:var(--sans);font-size:15px;line-height:1.7}button,input,textarea,select{font:inherit}button,a,input,textarea,select{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}a{color:inherit;text-decoration:none}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:4px}button{color:inherit}::selection{background:#d8e3ce}h1,h2,h3,h4,p{margin-top:0}h1,h2,h3{font-weight:600;line-height:1.35}small{font-size:12px}img,svg{max-width:100%}.muted{color:var(--muted)}.eyebrow{font-size:11px;letter-spacing:.15em;color:var(--accent);font-weight:600;text-transform:uppercase;margin-bottom:17px}.rule{border-top:1px solid var(--line)}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip-link{position:fixed;top:-60px;left:24px;background:var(--ink);color:white;padding:8px 16px;z-index:100}.skip-link:focus{top:8px}
.topbar{height:94px;display:flex;align-items:center;gap:45px;padding:0 max(30px,calc((100vw - 1380px)/2));border-bottom:1px solid var(--line);background:rgba(247,245,239,.97);position:sticky;top:0;z-index:30}.brand{display:flex;align-items:center;gap:12px;font-size:17px;font-weight:600;white-space:nowrap;color:var(--ink)}.brand small{display:block;font-size:8px;letter-spacing:.16em;font-weight:500;margin-top:2px}.brand-mark{font-family:Georgia,serif;font-size:33px;line-height:42px;text-align:center;display:block;width:43px;height:43px;border:1px solid var(--ink);border-radius:50%}.brand-mark span{color:var(--accent)}.topnav{display:flex;align-items:center;gap:28px;flex:1}.topnav a{font-size:13px;white-space:nowrap;color:var(--muted)}.topnav a:hover,.topnav a.active{color:var(--ink)}.topnav a.active{box-shadow:0 3px 0 -1px var(--accent);padding-bottom:6px}.search-trigger{display:flex;gap:25px;align-items:center;background:transparent;border:1px solid var(--line);padding:8px 12px;font-size:11px;color:var(--muted);border-radius:4px}.search-trigger kbd{font:10px var(--sans);color:#91968e}.shell{max-width:1260px;margin:auto;padding:0 34px}.hero{padding:80px 0 66px;display:grid;grid-template-columns:1.2fr 1fr;gap:80px;align-items:center}.hero h1{font:500 clamp(42px,4.4vw,64px)/1.22 var(--serif);letter-spacing:.015em;color:var(--ink);margin:0 0 24px}.hero h1 em{font-style:normal;color:var(--accent)}.hero-description{color:var(--muted);max-width:430px;font-size:15px;line-height:1.9}.actions{display:flex;gap:16px;align-items:center;flex-wrap:wrap;margin-top:28px}.button{display:inline-flex;align-items:center;justify-content:center;gap:18px;padding:12px 21px;border:1px solid var(--ink);background:var(--ink);color:var(--white);font-size:13px;border-radius:3px;transition:background .15s,transform .15s}.button:hover{background:#355347;transform:translateY(-1px)}.button.secondary{background:transparent;color:var(--ink);border-color:var(--line)}.button.secondary:hover{background:var(--soft)}.text-link{font-size:13px;color:var(--ink);border-bottom:1px solid #aeb7ac;padding-bottom:3px}.hero-map{padding:22px 0 8px;position:relative}.hero-map svg{width:100%;height:auto}.map-caption{display:flex;justify-content:space-between;font:10px var(--sans);letter-spacing:.05em;color:var(--muted);margin:5px 10px}.stats-strip{display:flex;align-items:center;border-block:1px solid var(--line);padding:24px 0;gap:38px}.stat{display:flex;gap:12px;align-items:baseline;padding-right:38px;border-right:1px solid var(--line)}.stat strong{font:32px var(--serif);color:var(--ink)}.stat span{font-size:12px;color:var(--muted)}.strip-note{margin-left:auto;font-size:12px;color:var(--muted);max-width:290px}.section-head{display:flex;align-items:end;justify-content:space-between;gap:25px;margin:56px 0 24px}.section-head h2{font:30px var(--serif);color:var(--ink);margin:0}.section-head p{font-size:13px;color:var(--muted);margin:0}.chapter-grid{display:grid;grid-template-columns:1fr 1fr;column-gap:44px}.chapter-row{display:flex;align-items:flex-start;gap:22px;padding:25px 0 24px;border-top:1px solid var(--line);transition:padding .2s}.chapter-row:hover{padding-left:7px}.chapter-number{font:29px var(--serif);color:#8a9a89;min-width:36px;margin-top:-2px}.chapter-row h3{font-size:17px;font-weight:500;margin-bottom:7px;color:var(--ink)}.chapter-row p{font-size:12px;color:var(--muted);margin-bottom:12px}.chapter-row .arrow{margin-left:auto;color:#929f91}.chapter-meta{font-size:10px;color:#7a837a;display:flex;gap:15px}.chapter-row progress{width:65px;height:3px;accent-color:var(--ink);align-self:center}.home-bottom{display:grid;grid-template-columns:1fr 1fr;gap:40px;padding:40px 0 64px}.feature-note{border-top:1px solid var(--line);padding:27px 0}.feature-note .eyebrow{margin-bottom:9px}.feature-note h3{font:23px var(--serif);color:var(--ink);margin-bottom:10px}.feature-note p{font-size:13px;color:var(--muted);max-width:480px}.site-footer{max-width:1260px;margin:auto;padding:26px 34px 34px;display:flex;gap:30px;border-top:1px solid var(--line);font-size:11px;color:var(--muted)}.site-footer span{flex:1}.page-header{padding:55px 0 38px;border-bottom:1px solid var(--line);margin-bottom:32px}.page-header h1{font:42px/1.3 var(--serif);color:var(--ink);margin-bottom:15px}.page-header p{max-width:680px;color:var(--muted);font-size:15px}.breadcrumb{font-size:11px;color:var(--muted);margin-bottom:24px}.breadcrumb a:hover{text-decoration:underline}.reading-layout{display:grid;grid-template-columns:214px minmax(0,740px) 160px;gap:35px;max-width:1380px;margin:auto;padding:34px 28px 60px}.side-nav{font-size:12px;position:sticky;top:123px;align-self:start;max-height:calc(100vh - 145px);overflow:auto;padding-right:12px}.side-nav .nav-label{font-size:9px;letter-spacing:.13em;color:#8a968c;margin:0 0 12px}.side-nav a{display:flex;gap:10px;padding:9px 11px;border-left:2px solid transparent;line-height:1.6;margin-bottom:3px;color:var(--muted)}.side-nav a.active{background:var(--soft);color:var(--ink);border-color:var(--ink);font-weight:600}.side-nav a:hover{background:#eef0e8}.side-nav .num{font-family:Georgia,serif;color:#879380}.side-nav .nav-divider{height:1px;background:var(--line);margin:20px 0}.reader{min-width:0}.reader-header{padding:12px 0 26px}.reader-header h1{font:38px/1.35 var(--serif);color:var(--ink);margin-bottom:15px}.reader-header .subtitle{font-size:15px;color:var(--muted);margin-bottom:20px}.reading-tabs{display:flex;gap:26px;align-items:center;border-bottom:1px solid var(--line);margin:24px 0}.reading-tabs a,.reading-tabs button{font-size:12px;padding:12px 0;border:0;background:transparent;color:var(--muted);cursor:pointer}.reading-tabs .selected{color:var(--ink);border-bottom:2px solid var(--ink)}.reader-tools{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin-bottom:26px}.small-button{padding:5px 9px;border:1px solid var(--line);background:transparent;border-radius:3px;font-size:11px}.small-button:hover{background:var(--soft)}.reader-intro{font:var(--reader)/1.95 var(--serif);color:var(--text);margin:20px 0 30px}.objective-list{border-block:1px solid var(--line);padding:20px 0;margin:28px 0;color:var(--muted);font-size:13px}.objective-list ul{margin:8px 0 0;padding-left:20px}.objective-list li{margin:7px 0}.unit{padding:28px 0 36px;border-bottom:1px solid var(--line);scroll-margin-top:112px}.unit-label{font-size:10px;color:var(--accent);letter-spacing:.07em;margin-bottom:11px}.unit h2{font:28px/1.4 var(--serif);color:var(--ink);margin-bottom:22px}.prose{font:var(--reader)/1.95 var(--serif);overflow-wrap:break-word}.prose p{margin-bottom:1.3em}.prose h2{font-size:27px;margin-top:1.9em}.prose h3{font-size:22px;margin-top:1.7em}.prose h4{font-size:19px;margin-top:1.6em}.prose ul,.prose ol{padding-left:1.4em}.prose li{margin:.65em 0}.prose strong{color:var(--ink);font-weight:700}.prose a{color:#4d6c53;border-bottom:1px solid #a6b69e}.prose blockquote{margin:24px 0;padding:10px 23px;border-left:2px solid #92a382;color:var(--muted)}.prose table{width:100%;border-collapse:collapse;font:13px/1.7 var(--sans);display:block;overflow-x:auto;margin:24px 0}.prose th,.prose td{padding:10px 14px;border:1px solid var(--line);text-align:left;min-width:100px}.prose th{background:var(--soft)}.prose pre{font:12px/1.75 "SFMono-Regular",Consolas,monospace;overflow-x:auto;background:#eef0e8;padding:20px;border:1px solid var(--line);border-radius:4px}.prose code{font-family:"SFMono-Regular",Consolas,monospace;font-size:.83em;background:#ecefe6;padding:1px 4px;border-radius:3px}.prose pre code{background:transparent;padding:0;font-size:inherit}.prose math{font-family:"STIX Two Math","Cambria Math",serif;max-width:100%;overflow:auto}.prose math[display=block]{display:block;margin:24px 0;padding:10px 0}.source-links{font-size:11px;color:var(--muted);display:flex;gap:8px;flex-wrap:wrap;margin:20px 0 8px;align-items:center}.source-links a{border:1px solid var(--line);padding:2px 7px;border-radius:3px}.source-links a:hover{background:var(--soft)}.supplement-tag{font-size:10px;color:var(--muted);letter-spacing:.08em}.diagram{background:#edf0e5;padding:23px 22px;margin:26px 0}.diagram h3{font-size:13px;font-weight:600;margin-bottom:21px}.diagram-flow{display:flex;align-items:stretch;gap:8px;flex-wrap:wrap}.diagram-node{flex:1;min-width:90px;border:1px solid #bac8b1;background:var(--white);padding:13px 10px;text-align:center;font-size:12px}.diagram-arrow{align-self:center;color:#8a9b7d}.diagram figcaption{font-size:11px;color:var(--muted);margin-top:16px;line-height:1.8}.recall{padding:22px 0 0}.recall h3{font-size:13px;font-weight:600;margin-bottom:11px}.recall .prompt{font-size:14px;line-height:1.85;margin-bottom:15px}.recall textarea,.note-input{width:100%;resize:vertical;min-height:98px;border:1px solid var(--line);background:var(--white);padding:13px 15px;border-radius:3px;font-size:13px;line-height:1.8;color:var(--text)}.recall details{margin-top:12px;font-size:13px}.recall summary{cursor:pointer;color:var(--ink);padding:5px 0}.answer{padding:12px 0;color:var(--muted);line-height:1.9;white-space:pre-wrap}.unit-actions{display:flex;flex-wrap:wrap;gap:18px;align-items:center;font-size:11px;margin-top:22px;color:var(--muted)}.unit-actions label{display:flex;align-items:center;gap:6px;cursor:pointer}.unit-actions input{accent-color:var(--ink);width:15px;height:15px}.unit-actions button{margin-left:auto}.margin-toc{position:sticky;top:130px;align-self:start;font-size:10px;color:var(--muted);max-height:calc(100vh - 155px);overflow:auto}.margin-toc h3{font-size:10px;font-weight:500;letter-spacing:.1em;margin-bottom:18px}.margin-toc a{display:block;padding:7px 0 7px 11px;border-left:1px solid var(--line);line-height:1.65}.margin-toc a:hover{border-color:var(--ink);color:var(--ink)}.margin-toc .reading-state{font-size:10px;margin-top:27px}.margin-toc progress{width:100%;height:4px;accent-color:var(--ink)}.application{margin:40px 0;border-block:1px solid #b9c4af;padding:27px 0}.application h2{font:27px var(--serif)}.application p{font:16px/1.9 var(--serif)}.application details{font-size:13px}.connections{display:flex;gap:12px;flex-wrap:wrap;margin:28px 0}.connection{flex:1;min-width:220px;border:1px solid var(--line);padding:17px}.connection small{color:var(--accent);font-size:9px}.connection strong{display:block;font-size:14px;margin:5px 0}.connection p{font-size:12px;color:var(--muted);margin:0}.editorial{margin:28px 0;font-size:12px;color:var(--muted);line-height:1.9}.editorial summary{cursor:pointer;color:var(--ink)}.editorial dt{margin-top:15px;font-weight:600}.editorial dd{margin-left:0}.source-anchor{display:block;color:#86917f;font:10px var(--sans);margin:24px 0 7px;scroll-margin-top:115px}.source-anchor:target{color:var(--accent)}.block-anchor{display:block;height:0;scroll-margin-top:115px}.source-prose h1{font-size:30px}.source-prose{font-size:var(--reader)}.source-warning{font-size:12px;color:var(--muted);padding:15px 0;border-block:1px solid var(--line);margin:20px 0}.course-list{margin:16px 0 55px}.course-item{display:grid;grid-template-columns:45px 1fr auto;align-items:start;gap:20px;padding:22px 0;border-bottom:1px solid var(--line)}.course-item h3{font-size:16px;margin:0 0 6px}.course-item p{margin:0;font-size:12px;color:var(--muted)}.course-item .course-buttons{display:flex;gap:13px;align-items:center;font-size:11px;flex-wrap:wrap}.course-id{font:24px var(--serif);color:#87947e}.chapter-group h2{font:25px var(--serif);margin-top:40px}.download-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:25px 0 50px}.download-link{display:flex;justify-content:space-between;gap:20px;padding:16px;border:1px solid var(--line);font-size:12px}.download-link:hover{background:var(--soft)}.about-prose{max-width:780px;margin-bottom:60px;font-size:15px;line-height:1.95}.about-prose h2{font:27px var(--serif);margin-top:35px}.about-prose ul{padding-left:21px}.about-prose li{margin:12px 0}.about-prose code{font-size:12px;background:var(--soft);padding:2px 5px}.notes-overview{display:flex;gap:45px;padding:8px 0 27px}.notes-overview strong{font:32px var(--serif);display:block;color:var(--ink)}.notes-overview span{font-size:12px;color:var(--muted)}.note-card{padding:25px 0;border-bottom:1px solid var(--line)}.note-card h3{font-size:17px;margin-bottom:12px}.note-card p{font-size:14px;white-space:pre-wrap;overflow-wrap:anywhere;color:var(--muted)}.empty-state{padding:55px 0 85px}.empty-state h2{font:27px var(--serif)}.empty-state p{color:var(--muted)}.lab{border:1px solid #bfcbb4;background:#f1f3eb;border-radius:4px;padding:23px;margin:25px 0 32px}.lab h3{font-size:16px;margin-bottom:9px}.lab p{font-size:12px;color:var(--muted);line-height:1.8}.lab-controls{display:flex;gap:18px;align-items:center;flex-wrap:wrap;margin:19px 0;font-size:12px}.lab-controls select{background:var(--white);border:1px solid var(--line);padding:5px}.lab-controls input[type=range]{max-width:170px;accent-color:var(--ink)}.attention-table{width:100%;border-collapse:collapse;font-size:12px;text-align:center;margin:15px 0}.attention-table th{font-size:10px;font-weight:500;padding:8px}.attention-table td{padding:15px 8px;border:3px solid #f1f3eb;font-variant-numeric:tabular-nums}.attention-table tr.selected th{color:var(--accent);font-weight:700}.value-output{font-size:12px;color:var(--ink);border-top:1px solid var(--line);padding-top:14px;margin-top:18px}.lab-explain{font-size:12px;color:var(--muted)}.loss-line{stroke:var(--ink);stroke-width:2.5;fill:none}.loss-point{fill:var(--accent);stroke:var(--white);stroke-width:2}.diagram-buttons{display:flex;gap:8px;flex-wrap:wrap}.diagram-buttons button{border:1px solid var(--line);padding:7px 11px;background:var(--white);font-size:11px}.diagram-buttons button.selected{background:var(--ink);color:var(--white)}.lab-case{font-size:13px;padding-top:20px;color:var(--ink);line-height:1.9}dialog{border:1px solid var(--line);background:var(--white);color:var(--text);padding:27px;width:min(690px,calc(100vw - 32px));max-height:80vh;border-radius:7px;box-shadow:0 20px 80px #16291d25}dialog::backdrop{background:#20332955;backdrop-filter:blur(3px)}.dialog-head{display:flex;justify-content:space-between;gap:15px}.dialog-head h2{font:22px var(--serif);margin-bottom:22px}.icon-button{border:0;background:transparent;font-size:26px;line-height:1}.dialog-head .icon-button{align-self:start}#search-input{width:100%;border:1px solid var(--line);padding:12px 15px;background:var(--paper);border-radius:3px;outline-offset:1px}#search-results{margin-top:18px;font-size:13px}.search-result{display:block;border-bottom:1px solid var(--line);padding:17px 0}.search-result strong{font-size:13px;display:block;margin:5px 0}.search-result small{font-size:10px;color:var(--accent)}.search-result p{font-size:12px;line-height:1.8;color:var(--muted);margin-bottom:0}.search-result mark{background:#e7e8c8;color:var(--ink)}#toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);background:var(--ink);color:var(--white);border-radius:4px;padding:10px 18px;font-size:12px;z-index:100;opacity:0;pointer-events:none;transition:opacity .15s}#toast.show{opacity:1}.loading{padding:100px 34px;text-align:center;color:var(--muted)}.mobile-chapter-select{display:none}.note-editor{margin-top:17px}.print-note{display:none}.error-state{padding:70px 30px;max-width:800px;margin:auto}.error-state h1{font-size:26px}.print-only{display:none}
@media(min-width:1600px){.reading-layout{max-width:1430px;grid-template-columns:228px minmax(0,780px) 180px;gap:45px}}
@media(max-width:1120px){.topbar{gap:25px}.topnav{gap:18px}.search-trigger span{display:none}.search-trigger{gap:0}.hero{gap:35px}.reading-layout{grid-template-columns:175px minmax(0,1fr);gap:28px}.margin-toc{display:none}.side-nav{font-size:11px}.reader-header h1{font-size:34px}.strip-note{max-width:250px}.stat{padding-right:24px}.stats-strip{gap:24px}}
@media(max-width:760px){.topbar{height:74px;padding:0 18px;gap:12px;flex-wrap:wrap;align-content:center}.brand{font-size:14px;gap:8px}.brand-mark{width:33px;height:33px;font-size:25px;line-height:33px}.brand small{font-size:6px}.topnav{margin-left:auto;gap:14px;flex:0}.topnav a{font-size:11px}.topnav a:nth-child(2),.topnav a:nth-child(4){display:none}.search-trigger{padding:5px 6px;font-size:11px}.shell{padding:0 23px}.hero{grid-template-columns:1fr;gap:15px;padding:42px 0 26px}.hero h1{font-size:43px}.hero-description{font-size:14px;max-width:100%}.hero-map{max-width:430px;margin:0 auto;width:100%}.hero-map svg{max-height:250px}.stats-strip{gap:17px;padding:20px 0;flex-wrap:wrap}.stat{padding-right:17px;gap:7px}.stat strong{font-size:27px}.stat span{font-size:10px}.strip-note{font-size:11px;margin:0;max-width:100%}.section-head{margin-top:36px;align-items:start}.section-head h2{font-size:26px}.section-head p{font-size:11px}.chapter-grid{grid-template-columns:1fr;gap:0}.chapter-row{padding:20px 0}.chapter-row h3{font-size:16px}.chapter-number{font-size:26px}.home-bottom{grid-template-columns:1fr;gap:0;padding:25px 0}.site-footer{padding:23px;gap:15px;flex-wrap:wrap}.site-footer span{flex-basis:100%;order:3}.page-header{padding-top:32px}.page-header h1{font-size:32px}.reading-layout{display:block;padding:20px 23px 45px}.side-nav{display:none}.mobile-chapter-select{display:block;width:100%;padding:9px 10px;background:transparent;border:1px solid var(--line);font-size:12px;margin-bottom:22px}.reader-header h1{font-size:32px}.reader-intro{font-size:17px}.unit h2{font-size:26px}.prose{font-size:17px;line-height:1.95}.source-prose{font-size:17px}.unit{padding:24px 0}.diagram{margin:24px 0;padding:17px}.diagram-node{min-width:85px}.diagram-arrow{font-size:12px}.lab{padding:16px}.course-item{grid-template-columns:30px 1fr;gap:12px}.course-item .course-buttons{grid-column:2}.course-item h3{font-size:14px}.download-grid{grid-template-columns:1fr}.notes-overview{gap:25px}.reading-tabs{gap:21px}.reader-tools{gap:6px}.unit-actions{gap:10px}.section-head .text-link{font-size:11px}.attention-table td{padding:13px 4px}.attention-table th{font-size:9px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{transition:none!important;animation:none!important}}
@media print{@page{size:A4;margin:18mm 18mm 20mm}body{background:white;color:#111;font-size:11pt}.topbar,.side-nav,.margin-toc,.site-footer,.reader-tools,.reading-tabs,.mobile-chapter-select,.unit-actions,.source-links,.lab-controls,.diagram-buttons,dialog,#toast,.recall textarea,.note-editor,.no-print{display:none!important}.reading-layout,.shell{display:block;max-width:none;padding:0;margin:0}.reader-header{padding:0}.reader-header h1{font-size:26pt}.reader-intro,.prose{font-size:11pt;line-height:1.7}.unit h2{font-size:18pt}.unit{padding:18px 0;border-bottom:1px solid #ccc}.prose p{orphans:3;widows:3}h1,h2,h3{break-after:avoid}.diagram,.lab{break-inside:avoid;background:#f5f5f1}.diagram-node{border-color:#aaa}.recall{break-inside:avoid}.recall .answer{display:block}.print-note,.print-only{display:block;font-size:9pt;color:#666}.source-anchor{font-size:7pt;color:#777}.page-header{padding:0}.chapter-grid{display:block}.course-buttons{display:none!important}a{color:inherit}.prose pre{white-space:pre-wrap;font-size:8pt}.prose table{display:table}details>summary{list-style:none}.hero{display:block;padding:0}.hero-map{display:none}.button,.search-trigger{display:none}.notes-overview{padding-bottom:15px}.source-warning{font-size:9pt}}

.chapter-visual{border-block:1px solid var(--line);padding:24px 0;margin:34px 0 10px}.chapter-visual h3{font:21px/1.6 var(--serif);color:var(--ink);margin:12px 0 7px}.chapter-visual svg{display:block;width:100%;height:auto}.chapter-visual figcaption{font-size:11px;line-height:1.9;color:var(--muted)}.margin-toc a.toc-current{border-left:2px solid var(--ink);background:var(--soft);color:var(--ink)}.reading-tabs>span{font-size:12px;padding:12px 0}.chapter-visual{break-inside:avoid}

.anchor-details{flex-basis:100%;margin-top:3px}.anchor-details summary{cursor:pointer;width:fit-content;padding:4px 0}.anchor-details>div{display:flex;flex-wrap:wrap;gap:6px;padding:8px 0}.anchor-details a{font-size:10px}

#chapter-practice{scroll-margin-top:112px}