/* Reading-first edition. Approved course colors and marks retained. */
:root{--reading-size:18px;--reading-leading:1.95;--reading-width:780px}
*{box-sizing:border-box}html{scroll-padding-top:110px}body{overflow-wrap:break-word}button,a,input,select,textarea{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}button:disabled{opacity:.5;cursor:not-allowed}button:focus-visible,a:focus-visible,summary:focus-visible,select:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid var(--strong);outline-offset:4px}button{font:inherit}.wrap{max-width:1180px;width:calc(100% - 64px);margin:0 auto}.topbar{background:var(--paper);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:50}.header-inner{max-width:1320px;height:86px;padding:0 28px;gap:19px}.brand .theme-logo{width:208px;height:auto}.producer-badge{display:flex!important;flex-direction:column;align-items:flex-start;gap:1px;white-space:nowrap}.producer-badge span{font-size:9px;font-weight:400;letter-spacing:1.5px;color:var(--muted)}.producer-badge img{width:86px;height:28px;object-fit:contain}.brand-divider{height:33px}#nav{gap:27px;margin-left:auto}#nav a{font-size:13px;color:var(--muted);padding:13px 0;border-bottom:2px solid transparent}#nav a[aria-current=page]{color:var(--ink);border-color:var(--strong)}.header-tools{gap:8px;margin-left:14px}.icon-button{width:38px;height:38px;border-radius:6px;color:var(--ink)}.btn{min-height:44px;padding:12px 21px;font-size:13px;font-weight:600;gap:12px;display:inline-flex;align-items:center;justify-content:center;line-height:1.5}.btn.secondary{border:1px solid var(--line);color:var(--ink);background:var(--surface)}.btn.secondary:hover{border-color:var(--strong);color:var(--strong)}.full{width:100%}.quiet-link{display:inline-flex;align-items:center;gap:10px;font-size:13px;color:var(--strong);font-weight:500}.quiet-link:hover{text-decoration:underline}.tool-button{display:inline-flex;align-items:center;justify-content:center;gap:7px;min-height:38px;padding:9px 12px;border:1px solid var(--line);border-radius:6px;background:var(--surface);font-size:12px;color:var(--ink);cursor:pointer}.eyebrow{font-size:10px;letter-spacing:2px;font-weight:500;color:var(--strong);line-height:1.6}.eyebrow:before{content:none}.pill{font-size:10px;letter-spacing:.2px;border:1px solid var(--line);background:var(--soft);color:var(--strong);padding:6px 10px;white-space:normal}.pill .dot{width:5px;height:5px;background:var(--strong)}.muted{color:var(--muted);line-height:1.8}.small-note{font-size:11px!important;line-height:1.8;color:var(--muted)}.hidden{display:none!important}
.book-hero{display:grid;grid-template-columns:1fr 1.05fr;align-items:center;gap:64px;padding:76px 0 64px}.book-hero h1{font-size:clamp(38px,4vw,56px);line-height:1.35;letter-spacing:-1.5px;margin:23px 0}.book-hero p{font-size:16px;line-height:2;color:var(--muted);margin:22px 0 28px}.book-hero .actions{align-items:center;gap:25px}.book-cover{margin:0}.book-cover img{display:block;width:100%;height:auto;border-radius:9px}.book-cover figcaption{font-size:12px;color:var(--muted);line-height:1.8;margin-top:13px}.book-edition{margin-top:35px;font-size:11px;color:var(--muted);display:flex;flex-wrap:wrap;gap:20px}.book-edition span{letter-spacing:1px;color:var(--strong)}.book-chapters{border-top:1px solid var(--line);padding:45px 0 75px}.book-chapters .section-head{margin-bottom:30px}.book-chapters h2{font-size:29px;margin-top:10px}.book-card-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}.book-chapter-card{border:1px solid var(--line);border-radius:8px;overflow:hidden;display:flex;flex-direction:column;background:var(--surface);transition:border-color .2s}.book-chapter-card:hover{border-color:var(--strong)}.book-card-image{background:#f6f3eb;aspect-ratio:3/2;display:flex;align-items:center}.book-card-image img{width:100%;height:100%;object-fit:contain}.book-card-copy{padding:23px;display:flex;flex-direction:column;flex:1}.book-card-copy h3{font-size:21px;line-height:1.65;margin:12px 0}.book-card-copy p{font-size:14px;line-height:1.9;color:var(--muted);margin:0 0 25px}.book-card-tail{margin-top:auto;display:flex;align-items:center;justify-content:space-between;font-size:12px;color:var(--strong)}.quiet-footer{display:flex;justify-content:space-between;gap:20px;border-top:1px solid var(--line);padding:28px 0;color:var(--muted);font-size:12px;line-height:1.8}
.reading-layout{display:grid;grid-template-columns:225px minmax(0,780px);gap:60px;max-width:1160px;padding:0 32px;margin:0 auto;align-items:start}.reading-sidebar{position:sticky;top:108px;padding:30px 0;max-height:calc(100dvh - 108px);overflow-y:auto;scrollbar-width:thin}.back-to-contents{display:inline-block;font-size:12px;color:var(--muted);margin-bottom:28px}.chapter-switch-label{display:block;font-size:10px;letter-spacing:1px;color:var(--muted);margin-bottom:10px}.reading-sidebar select{width:100%;min-height:42px;padding:10px 25px 10px 8px;font:inherit;font-size:12px;border:1px solid var(--line);border-radius:5px;background:var(--surface);color:var(--ink)}.reader-toc{display:flex;flex-direction:column;gap:4px;margin-top:24px;padding-bottom:20px}.reader-toc a,.mobile-toc a{display:flex;align-items:baseline;gap:12px;font-size:12px;line-height:1.85;padding:9px;color:var(--muted);border-radius:4px}.reader-toc a>span,.mobile-toc a>span{font-size:10px;min-width:17px}.reader-toc a[aria-current=location],.mobile-toc a[aria-current=location]{background:var(--soft);color:var(--strong)}.reading-center{min-width:0;padding:48px 0 70px}.reading-heading{border-bottom:1px solid var(--line);padding-bottom:34px;margin-bottom:42px}.reader-heading-top{display:flex;justify-content:space-between;gap:18px;align-items:center}.reader-tools{display:flex;gap:6px}.reading-heading h1{font-size:clamp(29px,3vw,39px);line-height:1.55;font-weight:650;letter-spacing:-.6px;margin:20px 0}.reading-meta{font-size:12px;color:var(--muted)}.translation-note{font-size:12px;color:var(--muted);margin-top:14px}.book-content{font-family:'PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif;font-size:var(--reading-size);line-height:var(--reading-leading);color:var(--ink)}.reading-section{margin-bottom:56px;scroll-margin-top:116px}.reading-section>h2{font-size:26px;line-height:1.6;font-weight:650;letter-spacing:-.3px;margin:0 0 27px}.book-content h3{font-size:21px;line-height:1.7;margin:32px 0 18px}.book-content h4{font-size:18px}.book-content p{margin:20px 0}.book-content ul,.book-content ol{padding-left:1.6em;margin:22px 0}.book-content li{padding-left:3px;margin:9px 0}.book-content a{color:var(--strong);text-decoration:underline;text-underline-offset:4px;text-decoration-color:#bcb3e4;overflow-wrap:anywhere}.book-content strong{font-weight:650}.book-content blockquote{margin:26px 0;padding:4px 22px;background:var(--soft);border-left:3px solid var(--strong);font-size:.94em}.book-content code{font-family:Consolas,monospace;background:var(--soft);font-size:.84em;border-radius:3px;padding:2px 5px;overflow-wrap:anywhere}.book-content pre{white-space:pre-wrap;overflow-wrap:anywhere;font-size:13px;border:1px solid var(--line);padding:15px}.reading-table{max-width:100%;overflow-x:auto;margin:27px 0;border:1px solid var(--line);border-radius:6px}.reading-table table{border-collapse:collapse;width:100%;min-width:420px;font-size:14px;line-height:1.85;margin:0}.reading-table th{background:var(--soft);text-align:left;color:var(--ink);font-weight:600}.reading-table th,.reading-table td{padding:14px 16px;border-bottom:1px solid var(--line);vertical-align:top}.reading-table tr:last-child td{border-bottom:0}
.book-content .textbook-figure{margin:32px auto 8px;width:100%;max-width:100%;break-inside:avoid}.book-content .figure-open{display:block;line-height:0;border:1px solid var(--line);border-radius:7px;overflow:hidden;background:#f7f4ea;cursor:zoom-in}.book-content .textbook-figure img{display:block;width:100%;height:auto;max-width:100%;object-fit:contain}.book-content .textbook-figure figcaption{font-size:12px;line-height:1.8;text-align:right;margin-top:8px}.book-content .figure-caption{font-size:13px;line-height:1.9;color:var(--muted);margin:8px 0 20px}.book-content .figure-relations{margin:10px 0 28px;font-size:12px;line-height:1.8}.figure-relations>summary{cursor:pointer;color:var(--muted);padding:6px 0}.textbook-diagram{margin:20px 0;padding:18px;border:1px solid var(--line);border-radius:6px;background:var(--soft)}.book-content .diagram-relations{list-style:none;padding:0;margin:0}.book-content .diagram-relations li{display:flex;align-items:center;gap:10px;flex-wrap:wrap;padding:12px 0;margin:0;border-bottom:1px solid var(--line);font-size:13px;line-height:1.8}.book-content .diagram-relations li:last-child{border:0}.diagram-node{font-weight:600}.diagram-arrow{color:var(--strong);font-size:18px}.diagram-label{color:var(--muted);font-size:11px}.diagram-source{margin-top:14px;font-size:12px}.diagram-source summary{cursor:pointer}.chapter-pagination{display:flex;justify-content:space-between;gap:20px;padding:26px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.chapter-pagination a{display:flex;flex-direction:column;gap:8px}.chapter-pagination a:last-child{text-align:right}.chapter-pagination span{color:var(--muted);font-size:12px}.chapter-pagination strong{font-size:16px;color:var(--strong);display:flex;align-items:center;gap:12px}.source-trail{font-size:12px;line-height:1.9;color:var(--muted);margin:24px 0}.source-trail summary{cursor:pointer}.source-trail a{display:inline-block;color:var(--muted);margin:8px 20px 0 0;text-decoration:underline;text-underline-offset:3px}.mobile-toc{display:none}
.reading-catalog{max-width:1000px;padding-bottom:70px}.reading-catalog .page-head{padding:50px 0 28px}.reading-catalog .page-head h1{font-size:42px}.search-box{display:flex;align-items:center;gap:12px;border:1px solid var(--line);border-radius:6px;padding:13px 17px;margin:0 0 30px;max-width:520px;background:var(--surface);color:var(--muted)}.search-box input{border:0;background:transparent;color:var(--ink);font:inherit;font-size:14px;min-width:0;width:100%;outline-offset:4px}.preface-banner{display:flex;gap:20px;align-items:center;padding:23px;background:var(--soft);border-radius:6px;line-height:1.8}.preface-banner span{font-size:11px;color:var(--strong)}.preface-banner strong{font-size:16px;font-weight:500}.preface-banner svg{margin-left:auto;flex-shrink:0}.catalog-part{font-size:20px;margin:36px 0 10px}.catalog-row{display:grid;grid-template-columns:45px minmax(0,1fr) 90px;gap:20px;align-items:start;padding:27px 0;border-bottom:1px solid var(--line)}.chapter-num{font-size:19px;color:var(--strong);padding-top:4px}.catalog-row h2{font-size:20px;line-height:1.7;font-weight:600;margin:0 0 9px}.catalog-row p{font-size:14px;line-height:1.9;color:var(--muted);margin:0}.catalog-action{padding-top:8px;text-align:right}.status-planned{font-size:12px;color:var(--muted)}.further-chapters{margin-top:32px}.further-chapters>summary{padding:14px 0;cursor:pointer;color:var(--muted);font-size:14px}.appendix-link{display:flex;align-items:center;gap:16px;font-size:14px;padding:25px 0;color:var(--strong);line-height:1.8}.search-snippet{margin-top:12px!important;background:var(--soft);padding:12px}.empty-inline{padding:30px 0;color:var(--muted)}
@media(max-width:1100px){.reading-layout{grid-template-columns:190px minmax(0,780px);gap:32px;padding:0 28px}.header-inner .producer-badge{display:none!important}.book-hero{gap:32px}.book-card-grid{gap:16px}.book-card-copy{padding:18px}}
@media(max-width:800px){.reading-layout{display:block;max-width:820px;padding:0 25px}.reading-sidebar{display:none}.reading-center{padding-top:28px}.mobile-toc{display:block;border-top:1px solid var(--line);margin-top:22px;padding-top:16px;font-size:13px}.mobile-toc summary{cursor:pointer;color:var(--strong)}.mobile-toc nav{position:static;display:flex;flex-direction:column;padding:12px 0;box-shadow:none;background:transparent;max-height:none}.book-hero{grid-template-columns:1fr;padding:42px 0;gap:32px}.book-cover{max-width:600px}.book-card-grid{grid-template-columns:1fr}.book-chapter-card{display:grid;grid-template-columns:40% 1fr}.book-card-image{height:100%;aspect-ratio:auto}.book-card-image img{height:auto}.book-hero h1{font-size:43px}.book-edition{margin-top:25px}.book-card-copy h3{font-size:20px}}
@media(max-width:600px){.wrap{width:calc(100% - 36px);padding-left:0;padding-right:0}.header-inner{height:72px;padding:0 15px;gap:8px}.brand,.brand .theme-logo{width:172px;height:auto}.brand-divider{display:none}.header-tools{margin-left:auto;gap:0}.icon-button{width:32px;height:36px}.topbar #nav{top:72px;margin-left:0;padding:12px 20px;gap:0}#nav a{font-size:14px;padding:12px 8px}.reading-layout{padding:0 20px}.reading-heading h1{font-size:29px}.reader-tools .tool-button{padding:7px 9px;min-height:34px}.reading-section>h2{font-size:23px}.book-content h3{font-size:19px}.reading-section{margin-bottom:43px;scroll-margin-top:95px}.book-hero h1{font-size:39px}.book-hero p{font-size:15px}.book-hero p br{display:none}.book-hero .actions{gap:20px;flex-wrap:wrap}.book-chapters{padding:32px 0 45px}.book-chapters h2{font-size:25px}.book-chapter-card{display:flex}.book-card-image{aspect-ratio:3/2}.book-card-image img{height:100%}.book-card-copy{padding:23px}.quiet-footer{font-size:11px;flex-direction:column;gap:4px}.catalog-row{grid-template-columns:28px minmax(0,1fr);gap:13px}.catalog-action{grid-column:2;text-align:left;padding-top:0}.catalog-row h2{font-size:18px}.preface-banner{flex-wrap:wrap;gap:9px;padding:18px}.preface-banner strong{font-size:14px}.reading-catalog .page-head h1{font-size:34px}.reading-table th,.reading-table td{padding:11px 12px}.book-content .textbook-figure{margin-top:24px}}
@media print{.topbar,#footer,.reading-sidebar,.reader-tools,.mobile-toc,.chapter-pagination,.source-trail,.figure-relations,.textbook-figure figcaption{display:none!important}.reading-layout{display:block;padding:0;max-width:none}.reading-center{padding:0}.reading-heading h1{font-size:24pt}.reading-heading{margin-bottom:25px}.book-content{font-size:12pt;line-height:1.7;color:#111}.reading-section>h2{break-after:avoid}.book-content .textbook-figure{break-inside:avoid}.book-content .figure-open{border:0}.book-content .figure-caption{color:#333}.reading-table{overflow:visible}.reading-table table{min-width:0}body{background:white}}
/* Scope navigation layout so the mobile header menu cannot affect book navigation. */
.reader-toc{align-items:stretch;margin-left:0;height:auto}.reader-toc a{height:auto}
.chapter-pagination{position:static;flex-direction:row;align-items:stretch;height:auto;margin-left:0;background:transparent;box-shadow:none}.chapter-pagination a{height:auto;align-items:flex-start}.chapter-pagination a:last-child{align-items:flex-end}
.mobile-toc nav{border:0;margin-left:0;align-items:stretch}.mobile-toc nav a{height:auto}
/* Keep the three 40px header controls reachable at 320px, including scrollbars. */
@media(max-width:360px){.header-inner .brand{flex:1 1 auto;min-width:0;width:auto}.header-inner .brand .theme-logo{width:100%;max-width:172px}.header-tools{flex-shrink:0}}
/* Reading path, chapter hierarchy and the book-end About page. */
html{scroll-padding-top:0}.wrap{padding-left:0;padding-right:0}.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}
#nav a{display:inline-flex;align-items:center;gap:7px;font-size:14px}.quiet-footer a{color:var(--strong);text-decoration:underline;text-underline-offset:4px}.book-hero .audience-line{font-size:17px;font-weight:600;color:var(--ink);margin-bottom:12px}.book-hero .audience-line+p{margin-top:0}.book-hero .home-guide{font-size:13px;margin:22px 0 0}.reading-path{display:flex;align-items:baseline;gap:30px;padding:23px 26px;background:var(--soft);border-radius:7px;margin-bottom:15px}.reading-path>span{color:var(--strong);font-size:13px;font-weight:600;flex-shrink:0}.reading-path ol{display:flex;gap:30px;flex-wrap:wrap;list-style:none;margin:0;padding:0;font-size:14px;line-height:1.9}.reading-path li+li:before{content:'→';color:var(--strong);margin-right:22px}.book-chapters{padding-bottom:50px;border-top:0}.book-chapters+.book-chapters{border-top:1px solid var(--line)}.book-chapters .section-head p{font-size:15px;max-width:700px;line-height:1.9;margin:10px 0 0}.book-card-tail,.book-cover figcaption{font-size:13px}.btn,.quiet-link{font-size:14px}.quiet-link{min-height:44px}
.part-description{font-size:14px;line-height:1.8;color:var(--muted);margin:8px 0 15px}.catalog-row h3{font-size:20px;line-height:1.7;font-weight:600;margin:0 0 9px}.catalog-row h3 a:hover,.search-result h3 a:hover{color:var(--strong);text-decoration:underline;text-underline-offset:5px}.catalog-time{display:block;color:var(--muted);font-size:12px;margin-top:10px}.preface-banner{flex-wrap:wrap}.preface-banner>span{flex-basis:100%;font-size:13px;font-weight:600}.reading-support{border-top:1px solid var(--line);margin-top:30px;padding-top:25px}.reading-support h2{font-size:20px}.appendix-link{justify-content:space-between;padding:22px 0;border-bottom:1px solid var(--line);font-size:16px}.appendix-link strong{font-weight:600}.appendix-link small{display:block;font-size:14px;color:var(--muted);margin-top:6px}.appendix-link svg{flex-shrink:0}.search-results-heading{font-size:22px;margin-bottom:10px}.search-count{font-size:14px;color:var(--muted)}.search-result{padding:25px 0;border-bottom:1px solid var(--line)}.search-result h3{font-size:20px;line-height:1.7;margin:0 0 10px}.search-result h3 a{color:var(--strong)}.search-result p{font-size:15px;line-height:1.9;margin:10px 0;color:var(--muted)}.search-result .search-section{font-size:13px;color:var(--strong)}
.reader-breadcrumb{font-size:13px;color:var(--strong);line-height:1.7;min-height:44px;display:flex;align-items:center;flex-wrap:wrap;gap:5px}.reader-breadcrumb span{color:var(--muted)}.reading-sidebar select{font-size:13px;min-height:44px}.back-to-contents{font-size:14px}.reader-toc a,.mobile-toc a{font-size:13px;min-height:44px}.reader-tools .tool-button{min-height:44px;min-width:44px;font-size:13px}.chapter-pagination{display:grid;grid-template-columns:1fr 1fr;padding:24px 0;gap:18px}.chapter-pagination a{padding:15px;border-radius:6px;min-width:0}.chapter-pagination a:hover{background:var(--soft)}.chapter-pagination .page-next{background:var(--soft)}.chapter-pagination span{font-size:13px;line-height:1.8}.chapter-pagination strong{font-size:17px;line-height:1.7}.reading-section{scroll-margin-top:110px}.source-trail summary{padding:10px 0;min-height:44px}.reading-heading{margin-bottom:32px}
@media(max-width:800px){.reading-path{align-items:flex-start;flex-direction:column;gap:12px}.reading-path ol{display:flex;flex-direction:column;gap:8px}.reading-path li+li:before{content:none}.reading-path li:before{content:'•';color:var(--strong);margin-right:10px}.mobile-toc{position:sticky;top:86px;z-index:30;margin:0 0 28px;padding:0;background:var(--paper);border:1px solid var(--line);border-radius:5px;box-shadow:0 3px 8px #00000005}.mobile-toc summary{padding:14px 12px;font-size:13px;line-height:24px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.mobile-toc summary span{color:var(--muted);margin-left:12px}.mobile-toc nav{max-height:55dvh;overflow-y:auto;padding:0 8px 12px;overscroll-behavior:contain}.mobile-toc[open] summary{border-bottom:1px solid var(--line)}.reading-section{scroll-margin-top:154px}.reading-heading{margin-bottom:20px}.reader-breadcrumb span{display:none}}
@media(max-width:760px){.topbar #nav{top:86px;margin-left:0;gap:0}#nav a{display:flex}.chapter-pagination{display:grid;padding:20px 0;border-bottom:1px solid var(--line)}}
@media(max-width:600px){.mobile-toc{top:72px}.topbar #nav{top:72px}.book-hero .audience-line{font-size:16px}.reading-path{padding:20px}.catalog-row h3,.search-result h3{font-size:18px}.chapter-pagination{grid-template-columns:1fr}.chapter-pagination a{padding:15px}.chapter-pagination a:last-child{align-items:flex-start;text-align:left}.reading-section{scroll-margin-top:140px}.reading-meta{font-size:13px}.reading-support h2{font-size:19px}.reader-heading-top{gap:10px}.quiet-footer{font-size:12px;gap:10px}}
@media print{.reading-path,.reader-breadcrumb{display:none!important}}