:root{--ink:#173348;--muted:#526779;--paper:#eff4f8;--white:#fff;--teal:#147a7c;--accent:#bd642b;--line:#ccd9e3;font-family:"Microsoft YaHei","PingFang SC",sans-serif;color:var(--ink);background:var(--white);font-size:16px;line-height:1.7}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:78px}body{margin:0}a{color:var(--teal);text-decoration:none}a:hover{text-decoration:underline}button,input,select{font:inherit}button,a,input,select,summary{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid var(--accent);outline-offset:4px}img{max-width:100%;display:block}button{color:var(--ink)}.wrap{width:min(1240px,calc(100% - 80px));margin:auto}.top{padding:22px 40px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line)}.brand{font-weight:700;color:var(--ink);letter-spacing:.06em}.brand span{font-weight:400;font-size:12px;letter-spacing:.1em;margin-left:20px;color:var(--muted)}.book-link{font-size:14px}.hero{display:grid;grid-template-columns:.8fr 1.2fr;gap:30px;align-items:center;padding-block:70px 60px}.eyebrow{font-size:12px;font-weight:700;letter-spacing:.12em;color:var(--teal);margin:0 0 14px}h1,h2,h3,p,figure{margin-top:0}h1{font-family:"SimSun","Songti SC",serif;font-size:clamp(40px,4.3vw,62px);line-height:1.25;letter-spacing:.03em;margin-bottom:26px}h2{font-size:30px;line-height:1.4;margin:0;letter-spacing:-.025em}h3{font-size:19px;line-height:1.6;margin-bottom:10px}.lead{font-size:17px;color:var(--muted);line-height:1.95}.actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:30px}.primary,.secondary{display:inline-flex;align-items:center;justify-content:center;padding:11px 18px;border:1px solid var(--line);border-radius:5px;background:var(--white);font-size:14px;font-weight:600;text-decoration:none!important}.primary{background:var(--teal);color:white;border-color:var(--teal)}.primary:hover{background:var(--ink)}.secondary:hover{background:var(--paper)}.edition{margin:24px 0 0;font-size:12px;color:var(--muted)}.hero-art{margin:0;position:relative;min-width:0}.hero-art a{display:block;position:relative}.hero-art img{width:100%;height:330px;object-fit:contain}.art-action{position:absolute;right:12px;bottom:14px;background:var(--white);border:1px solid var(--line);border-radius:30px;padding:8px 18px;font-size:13px;box-shadow:0 3px 16px #17334812}.hero-art figcaption{display:flex;justify-content:space-between;gap:12px;padding:16px 4px 0;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}.section-nav{position:sticky;top:0;z-index:3;background:var(--ink);color:white}.section-nav .wrap{display:flex;gap:44px}.section-nav a{color:white;padding:16px 0;font-size:14px}.section{padding-block:70px}.section-title{display:flex;justify-content:space-between;gap:24px;align-items:end;margin-bottom:26px}.section-title>a,.section-title>p{font-size:14px;margin:0;flex-shrink:0}.feature-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px}.feature{color:var(--ink);border:1px solid var(--line);border-radius:8px;overflow:hidden;transition:box-shadow .2s}.feature:hover{text-decoration:none;box-shadow:0 12px 26px #17334810}.feature>img{height:260px;width:100%;object-fit:contain;background:white;padding:12px}.feature>div{padding:22px 26px;background:var(--paper)}.tag{font-size:12px;color:var(--teal);font-weight:600}.feature h3{margin:8px 0}.feature p{color:var(--muted);font-size:14px;margin-bottom:20px}.go{font-size:14px;font-weight:700;color:var(--teal)}.model-strip{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;margin-top:30px}.model-strip a{border:1px solid var(--line);border-radius:8px;padding:12px;color:var(--ink)}.model-strip img{width:100%;height:170px;object-fit:contain}.model-strip span{display:flex;flex-direction:column;font-size:12px;color:var(--muted);padding:10px 8px}.model-strip b{font-size:17px;color:var(--ink);margin-bottom:4px}.catalog{border:1px solid var(--line);border-radius:6px;margin-top:30px;background:var(--white)}summary{cursor:pointer;padding:20px 24px;font-weight:600}summary span{font-weight:400;color:var(--muted);font-size:13px;margin-left:20px}.catalog-body{padding:0 24px 24px}.filters{display:flex;gap:20px}label{display:block;font-size:13px;color:var(--muted)}input,select{display:block;width:100%;margin-top:6px;border:1px solid var(--line);border-radius:4px;background:white;color:var(--ink);padding:9px 12px;min-height:44px}.search{flex:1}.filters>label:first-child{min-width:210px}.result-count{font-size:12px;color:var(--muted);margin:14px 0}.lesson-list{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.lesson-list a{padding:16px;background:var(--paper);border-radius:4px;font-size:14px;color:var(--ink)}.lesson-list small{display:block;color:var(--muted);font-size:11px;margin-bottom:6px}.more{display:flex;margin:24px auto 0}.cinema{background:var(--paper)}.intro{color:var(--muted);font-size:14px;max-width:880px;margin-bottom:24px}.tabs{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:26px}.tabs button{padding:10px 18px;border:1px solid var(--line);background:transparent;border-radius:5px;font-size:14px}.tabs button[aria-pressed=true]{background:var(--ink);color:white;border-color:var(--ink)}.tabs span{font-size:12px;opacity:.8;margin-left:8px}.screen-layout{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(270px,1fr);gap:28px;align-items:start}.screen-column{min-width:0}video{width:100%;aspect-ratio:16/9;display:block;background:#fff;border:1px solid var(--line);border-radius:7px}.now-playing{padding:22px 0 0}.now-playing h3{margin:6px 0;font-size:22px}.now-playing p{font-size:13px;color:var(--muted)}.video-links{display:flex;gap:24px;font-size:13px;flex-wrap:wrap}.playlist{padding:20px;border:1px solid var(--line);border-radius:7px;background:white}.playlist #video-list{max-height:450px;overflow:auto}.video-item{display:flex;gap:12px;align-items:center;width:100%;padding:12px 8px;text-align:left;background:white;border:0;border-bottom:1px solid var(--line);border-left:3px solid transparent}.video-item[aria-pressed=true]{background:var(--paper);border-left-color:var(--teal)}.video-item img{width:86px;aspect-ratio:16/9;object-fit:contain;flex-shrink:0}.video-item b{display:block;font-size:13px;font-weight:500;line-height:1.6}.video-item small{font-size:11px;color:var(--muted)}.image-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}.image-card{min-width:0;border:1px solid var(--line);border-radius:7px;overflow:hidden}.image-card button{display:block;background:white;border:0;padding:0;width:100%;position:relative}.image-card img{width:100%;height:220px;object-fit:contain}.image-card .image-copy{padding:16px 18px}.image-card h3{font-size:16px;margin:0}.image-card p{font-size:12px;color:var(--muted);margin:8px 0 0}.image-card .badge{position:absolute;top:10px;left:10px;font-size:11px;background:#fff;padding:3px 9px;border:1px solid var(--line);border-radius:3px;color:var(--ink)}.image-card .badge.warning{color:var(--accent)}.image-card small{font-size:11px;color:var(--muted)}.status{background:var(--paper)}.status-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:40px;margin-top:40px}.status-number{font-size:28px;color:var(--teal);font-family:Georgia,serif}.status-grid h3{margin-top:12px}.status-grid p{font-size:14px;color:var(--muted)}.status-grid a{font-size:13px}.status-grid #notebook-links a{display:block;margin-top:8px}.prose p{font-size:14px;max-width:980px;line-height:1.9}.footer{padding-block:40px;display:flex;justify-content:space-between;gap:24px;font-size:13px}.footer p{color:var(--muted);margin:5px 0}.footer a{margin-left:24px}dialog{padding:24px;border:1px solid var(--line);border-radius:8px;width:min(1150px,94vw);max-height:94vh;color:var(--ink)}dialog::backdrop{background:#173348c9}.dialog-bar{display:flex;gap:20px;align-items:center;justify-content:space-between;margin-bottom:14px}.dialog-bar h2{font-size:20px}.dialog-bar button{flex-shrink:0;padding:8px 14px;background:var(--paper);border:1px solid var(--line);border-radius:4px}#lightbox-image{width:100%;max-height:65vh;object-fit:contain}#lightbox-note{font-size:13px;color:var(--muted);margin-top:20px}dialog>a{font-size:13px}.skip{position:fixed;top:-80px;left:20px;z-index:20;background:white;padding:10px}.skip:focus{top:10px}[hidden]{display:none!important}
@media(min-width:1500px){.hero-art img{height:370px}}
@media(max-width:850px){.wrap{width:calc(100% - 40px)}.top{padding:18px 20px}.hero{gap:10px;grid-template-columns:1fr;padding-block:40px}.hero-copy{max-width:600px}.hero-art img{height:280px}.hero-art{margin-top:16px}.section{padding-block:46px}.section-title{align-items:start;flex-direction:column;gap:12px}h2{font-size:26px}.screen-layout{grid-template-columns:1fr}.playlist #video-list{max-height:330px}.image-grid{grid-template-columns:repeat(2,1fr)}.status-grid{gap:22px}.feature>img{height:180px}.feature>div{padding:18px}.model-strip{gap:12px}.model-strip img{height:130px}.lesson-list{grid-template-columns:repeat(2,1fr)}}
@media(max-width:540px){.brand span{display:block;margin:3px 0 0;font-size:10px}.hero{padding-top:32px}h1{font-size:43px}.lead{font-size:15px}.desktop{display:none}.hero-art img{height:220px}.hero-art figcaption{font-size:10px}.art-action{font-size:12px;padding:6px 12px}.section-nav .wrap{gap:0;justify-content:space-between}.section-nav a{font-size:13px;padding:14px 0}.feature-grid,.status-grid{grid-template-columns:1fr}.feature>img{height:205px}.model-strip{grid-template-columns:1fr}.model-strip a{display:flex;align-items:center}.model-strip img{width:42%;height:115px}.model-strip span{padding-left:16px}.tabs{gap:7px}.tabs button{font-size:12px;padding:9px 10px}.tabs span{margin-left:3px}.image-grid{gap:12px}.image-card img{height:145px}.image-card .image-copy{padding:12px}.image-card h3{font-size:13px}.image-card .badge{font-size:10px;top:5px;left:5px}.image-card p{font-size:11px}.filters{flex-direction:column;gap:12px}.lesson-list{grid-template-columns:1fr}summary{padding:18px;font-size:14px}summary span{display:block;margin:6px 0 0}.catalog-body{padding-inline:18px}.footer{flex-direction:column}.footer a{margin:0 20px 0 0}.dialog-bar h2{font-size:16px}dialog{padding:16px}.section-title>a{font-size:12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}

.reading-entry{padding-bottom:0}.reading-links{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}.reading-links a{display:flex;flex-direction:column;padding:22px;background:var(--paper);border-left:3px solid var(--teal);border-radius:3px}.reading-links b{font-size:16px}.reading-links span{font-size:13px;color:var(--muted);margin-top:8px}.reading-doc{max-width:940px}.reading-doc .article-head{padding-block:60px 35px}.reading-doc h1{font-size:42px}.reading-doc .body-text{font-size:17px;line-height:2.05;max-width:760px}.reading-doc h2{font-size:25px;margin:40px 0 20px}.reading-doc figure{margin:26px 0;border:1px solid var(--line);padding:18px;border-radius:6px}.reading-doc figure img{max-height:560px;width:100%;object-fit:contain}.reading-doc figcaption{font-size:13px;color:var(--muted);margin-top:15px}.reading-doc .equation{font-size:19px;background:var(--paper);padding:20px;font-family:Georgia,"Microsoft YaHei",sans-serif}.reading-doc iframe{width:100%;height:760px;border:1px solid var(--line);margin-top:20px;border-radius:6px}.reading-doc pre{overflow:auto;background:var(--paper);padding:20px;font-size:14px;line-height:1.8}.reading-doc .caption{font-size:13px;color:var(--muted)}.reading-doc .review-note{background:var(--paper);padding:24px;margin:40px 0}.reading-doc .review-note h2{margin-top:0}.reading-doc .actions{margin-block:20px}@media(max-width:700px){.reading-links{grid-template-columns:1fr;gap:12px}.reading-doc h1{font-size:32px}.reading-doc .body-text{font-size:16px}.section-nav .wrap{gap:14px;overflow:auto}.section-nav a{white-space:nowrap;flex-shrink:0}.reading-doc iframe{height:850px}}

.topic-links{font-size:13px;margin:20px 0 0}

.player-shell{position:relative}.player-shell #start-video{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);box-shadow:0 4px 24px #17334833;white-space:nowrap}
