:root{--paper:#f5f2eb;--card:#fffcf7;--ink:#262d29;--muted:#71766d;--rule:#dfded3;--green:#345c4c;--line:#dfded3;--serif:Georgia,"Songti SC","STSong","Noto Serif CJK SC",serif;--shell-bar:72px}
body{background:var(--paper);color:var(--ink)}
.skip{position:absolute;left:16px;top:8px;transform:translateY(-200%);z-index:100}
.skip:focus{transform:none;background:var(--card);padding:8px 12px}
.site-mast{width:min(1120px,calc(100% - 28px));margin:0 auto;padding:12px 0;display:flex;flex-wrap:wrap;align-items:center;gap:8px 18px;border-bottom:1px solid var(--rule);min-width:0}
.site-mast a.brand{display:inline-flex;gap:10px;align-items:center;color:var(--ink);text-decoration:none;min-height:44px}
.brand-mark{width:32px;height:38px;display:grid;place-items:center;border:1px solid #b5b6a5;color:var(--green);border-radius:2px 7px 7px 2px;box-shadow:3px 0 0 var(--paper),4px 0 0 #b5b6a5;font:20px var(--serif)}
.brand-name{display:block;font-size:12px;letter-spacing:1.6px;font-weight:650}
.brand-sub{display:block;color:var(--muted);font-size:9px;letter-spacing:1.8px}
.crumbs{display:flex;flex-wrap:wrap;gap:4px 0;align-items:center;flex:1 1 240px;min-width:0;font-size:14px;line-height:1.45}
.crumbs a,.crumbs span{color:var(--ink);text-decoration:none;min-height:44px;display:inline-flex;align-items:center}
.crumbs a+a::before,.crumbs span::before{content:"/";color:var(--muted);margin:0 8px;font-family:var(--serif)}
.crumbs span{color:var(--green);font-weight:650}
.catalog-link{margin-left:auto;min-height:44px;display:inline-flex;align-items:center;padding:0 12px;border:1px solid var(--rule);border-radius:4px;background:var(--card);color:var(--green);text-decoration:none;font-size:14px}
.chapter-turn{width:min(1120px,calc(100% - 28px));margin:12px auto;display:flex;flex-wrap:wrap;gap:8px;min-width:0}
.chapter-turn a{flex:1 1 280px;max-width:100%;min-width:0;min-height:44px;display:flex;flex-direction:column;justify-content:center;gap:2px;padding:8px 12px;border:1px solid var(--rule);border-radius:4px;background:var(--card);color:var(--ink);text-decoration:none}
.chapter-turn a span:first-child{color:var(--green);font-size:12px}
.turn-title{font-size:14px;line-height:1.4;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.reading-toolbar{background:var(--paper)}
.section-tabs{position:sticky;top:var(--shell-bar);z-index:9;background:var(--paper)}
.contents details{top:calc(var(--shell-bar) + 12px)}
html{scroll-padding-top:calc(var(--shell-bar) + 20px)}
.lesson,.hero h1,#section-tabs,.lesson-header{scroll-margin-top:calc(var(--shell-bar) + 20px)}
body.book-page,body.landing-page,body.aux-page{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}
.book-wrap{width:min(1120px,calc(100% - 28px));margin:0 auto;padding:0 0 48px;min-width:0}
.book-intro{display:flex;align-items:flex-end;justify-content:space-between;gap:18px 28px;padding:22px 0 16px}
.book-intro .eyebrow,.landing-page .eyebrow{margin:0 0 6px;color:var(--green);font-size:11px;letter-spacing:2px}
.book-intro h1,.landing-page h1{margin:0 0 8px;font:500 clamp(32px,4vw,46px)/1.25 var(--serif);letter-spacing:1px}
.book-intro p,.landing-page .lead{margin:0;color:var(--muted);font-size:15px;line-height:1.6;max-width:68ch}
.start{flex:0 0 auto;min-height:44px;display:inline-flex;align-items:center;padding:0 16px;background:var(--green);color:#fff;text-decoration:none;border-radius:4px}
.chapter-section{margin:8px 0 22px}
.chapter-section h2{margin:0 0 12px;font:500 22px/1.3 var(--serif)}
.chapter-grid{display:grid;grid-template-columns:1fr;gap:12px}
.chapter-card{display:flex;flex-direction:column;min-width:0;background:var(--card);border:1px solid #e5e4da;border-radius:6px;overflow:hidden;color:inherit;text-decoration:none}
.chapter-card img{width:100%;height:auto;aspect-ratio:3/2;object-fit:cover;background:#e7eee6;display:block}
.chapter-card div{padding:12px 14px 14px;min-width:0}
.chapter-card .num{color:var(--green);font-size:12px;font-weight:650}
.chapter-card h3{margin:4px 0;font:600 18px/1.4 var(--serif)}
.chapter-card .original,.chapter-card .blurb{margin:0;color:var(--muted);font-size:13px;line-height:1.55}
.chapter-card .blurb{display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;margin-top:4px}
.materials{margin-top:8px;border:1px solid var(--rule);border-radius:6px;background:var(--card);padding:0 14px}
.materials summary{min-height:48px;display:flex;align-items:center;cursor:pointer;font-weight:650}
.materials ul{list-style:none;margin:0;padding:0 0 12px}
.materials li{padding:10px 0;border-top:1px solid var(--rule)}
.materials a{color:var(--green)}
.materials .pages{display:block;color:var(--muted);font-size:13px}
.landing-nav,.material-groups{display:grid;grid-template-columns:1fr;gap:12px;margin:16px 0}
.landing-nav a,.material-groups section{display:block;min-width:0;background:var(--card);border:1px solid #e5e4da;border-radius:6px;padding:14px 16px;color:inherit;text-decoration:none}
.material-groups h2{margin:0 0 8px;font:500 20px/1.3 var(--serif)}
.material-groups ul{margin:0;padding-left:1.1em}
.aux-page .hero{padding:22px 0 8px}
.aux-page .hero h1{font:500 clamp(28px,4vw,40px)/1.3 var(--serif);letter-spacing:0}
.aux-page main{width:min(760px,calc(100% - 28px))}
.aux-page .topbar{display:none}
a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #a67d42;outline-offset:3px}
@media(min-width:760px){.chapter-grid{grid-template-columns:1fr 1fr}.landing-nav{grid-template-columns:1fr 1fr}}
@media(min-width:1100px){.chapter-grid{grid-template-columns:1fr 1fr 1fr}}
@media(max-width:420px){.site-mast,.chapter-turn,.book-wrap,.aux-page main{width:calc(100% - 20px)}.catalog-link{margin-left:0}.book-intro{display:block}.start{margin-top:12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}