:root{
  --navy:#1a3a56; --navy-2:#24507a; --navy-ink:#13283c;
  --gold:#a48748; --gold-soft:#d8d2bf; --gold-wash:#f6f2e7;
  --sumi:#4d4d54; --ink:#1f2328; --muted:#6b6f76;
  --red:#c0392b; --red-wash:#fbecea;
  --bg:#ffffff; --band:#f3f5f8; --line:#e3e6ea;
  --serif:"Noto Serif TC","Songti TC","PMingLiU",serif;
  --sans:"Noto Sans TC","PingFang TC","Microsoft JhengHei",system-ui,sans-serif;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:72px}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.75 var(--sans);font-feature-settings:"palt" 0}
img{max-width:100%;height:auto;display:block}
a{color:var(--navy-2)}
.skip{position:absolute;left:-999px;top:0;background:#fff;padding:8px 12px;z-index:99}
.skip:focus{left:8px}
:focus-visible{outline:3px solid var(--gold);outline-offset:2px}

/* ---- CIS brand bar (danlu-brand-chrome) ---- */
.brand-bar{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:12px 16px;max-width:1080px;margin:0 auto;border-bottom:1px solid var(--gold-soft)}
.brand-bar-left{display:flex;flex-direction:column;gap:2px;text-decoration:none}
.brand-bar-zh{color:#4d4d54;letter-spacing:.3em;font-size:14px;line-height:1.3}
.brand-bar-en{color:#a48748;letter-spacing:.22em;font-size:10.5px;font-weight:400;line-height:1.3;white-space:nowrap}
.brand-bar-slogan{color:#a48748;letter-spacing:.25em;font-size:12px;white-space:nowrap}
.brand-tagline{text-align:center;padding:16px;font-size:12px;color:#4d4d54;letter-spacing:.4em;border-top:1px solid var(--gold-soft);max-width:1080px;margin:0 auto}
@media (max-width:420px){.brand-bar-slogan{font-size:11px;letter-spacing:.12em}.brand-bar-zh{letter-spacing:.22em;font-size:13px}.brand-bar-en{letter-spacing:.12em;font-size:9.5px}}

/* ---- volume nav ---- */
.volnav{display:flex;max-width:1080px;margin:0 auto;padding:0 8px;overflow-x:auto;scrollbar-width:none}
.volnav::-webkit-scrollbar{display:none}
.volnav a{flex:1 0 auto;text-align:center;padding:10px 12px 9px;color:var(--sumi);text-decoration:none;font-size:15px;border-bottom:3px solid transparent;white-space:nowrap}
.volnav a span{margin-left:.4em;color:var(--muted);font-size:13px}
.volnav a[aria-current]{color:var(--navy);border-bottom-color:var(--navy);font-weight:700}
.volnav a:hover{color:var(--navy)}
main{max-width:1080px;margin:0 auto;padding:0 16px 40px}
.crumbs{font-size:13px;color:var(--muted);padding:14px 0 0;display:flex;gap:.5em;flex-wrap:wrap}
.crumbs a{color:var(--muted)}

/* ---- home ---- */
.hero{padding:40px 0 24px;border-bottom:1px solid var(--line)}
.hero h1{font-family:var(--serif);font-weight:900;font-size:clamp(30px,7vw,52px);line-height:1.25;letter-spacing:.04em;margin:0 0 14px;color:var(--navy-ink)}
.hero .lead{max-width:34em;color:var(--sumi);margin:0;font-size:16px}
.books{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;padding:28px 0 8px}
.book{display:flex;flex-direction:column;text-decoration:none;color:inherit;border:1px solid var(--line);background:#fff;min-height:230px;transition:transform .15s ease,border-color .15s}
.book:hover{border-color:var(--gold);transform:translateY(-2px)}
.book-band{background:var(--navy);border-bottom:4px solid var(--gold);height:104px;display:flex;align-items:center;padding:0 20px}
.book-roman{font-family:var(--serif);color:#fff;font-size:58px;line-height:1;font-weight:500}
.book-body{display:flex;flex-direction:column;padding:28px 18px 18px;gap:4px}
.book-k{font-size:13px;color:var(--muted)}
.book-t{font-family:var(--serif);font-size:24px;font-weight:700;color:var(--navy-ink);line-height:1.35}
.book-m{font-size:14px;color:var(--gold);margin-top:auto;padding-top:10px}
.howto,.errata{padding:28px 0 4px}
.howto h2,.errata h2{font-family:var(--serif);font-size:20px;margin:0 0 10px;color:var(--navy-ink)}
.howto ol{margin:0;padding-left:1.4em;color:var(--sumi)}
.howto li{margin:2px 0}
.howto b{color:var(--ink)}
.errata p{color:var(--sumi);margin:0 0 6px;font-size:15px}
.errata ul{margin:0;padding-left:1.2em;color:var(--sumi);font-size:15px}
.errata li{margin:4px 0}
@media (max-width:720px){
  .books{grid-template-columns:1fr;gap:12px}
  .book{flex-direction:row;min-height:0}
  .book-band{height:auto;width:76px;flex:0 0 76px;border-bottom:0;border-right:4px solid var(--gold);align-items:center;justify-content:center;padding:0}
  .book-roman{transform:none;font-size:44px}
  .book-body{padding:14px 16px}
  .book-t{font-size:21px}
  .book-m{padding-top:4px}
}

/* ---- volume TOC ---- */
.vol-head{display:flex;gap:18px;align-items:center;padding:22px 0 18px;border-bottom:1px solid var(--line)}
.vol-roman{font-family:var(--serif);font-size:56px;line-height:1;color:#fff;background:var(--navy);width:84px;height:96px;display:flex;align-items:center;justify-content:center;border-bottom:4px solid var(--gold);flex:0 0 auto}
.vol-k{margin:0;color:var(--muted);font-size:14px}
.vol-head h1{font-family:var(--serif);font-size:clamp(26px,6vw,38px);margin:2px 0 4px;color:var(--navy-ink);line-height:1.25}
.vol-meta{margin:0;color:var(--sumi);font-size:14px}
.toc-tip{margin:14px 0 0;font-size:13px;color:var(--muted)}
.sem h2{font-family:var(--serif);font-size:19px;color:var(--navy);margin:26px 0 6px;padding-left:10px;border-left:4px solid var(--gold)}
.toc{list-style:none;margin:0;padding:0}
.toc a{display:flex;align-items:baseline;gap:10px;padding:13px 4px;border-bottom:1px solid var(--line);text-decoration:none;color:var(--ink)}
.toc a:hover{background:var(--band)}
.toc-n{color:var(--muted);font-size:14px;flex:0 0 auto;min-width:4.2em}
.toc-t{font-family:var(--serif);font-size:18px;font-weight:700;flex:0 1 auto}
.toc-l{flex:1 1 auto;border-bottom:1px dotted #b9b2a0;transform:translateY(-5px);min-width:12px}
.toc-c{flex:0 0 auto;color:var(--sumi);font-size:14px}
.toc-p{flex:0 0 auto;color:var(--gold);font-size:14px;min-width:3.6em;text-align:right}
@media (max-width:480px){.toc-n{min-width:3.6em;font-size:13px}.toc-t{font-size:16.5px}.toc-c{display:none}}

/* ---- chapter ---- */
.ch-head{padding:14px 0 16px}
.ch-k{margin:0;color:var(--gold);font-size:15px;letter-spacing:.06em}
.ch-head h1{font-family:var(--serif);font-weight:900;font-size:clamp(28px,7vw,42px);line-height:1.25;margin:2px 0 8px;color:var(--navy-ink)}
.ch-meta{margin:0;display:flex;gap:16px;color:var(--sumi);font-size:14px}
.tools{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.96);backdrop-filter:saturate(1.4) blur(6px);display:flex;align-items:center;gap:10px;padding:8px 0;border-bottom:1px solid var(--line);border-top:1px solid var(--line)}
.jump{display:flex;align-items:center;gap:6px;font-size:14px;color:var(--sumi)}
.jump input{width:3.4em;font:inherit;font-size:16px;text-align:center;padding:5px 4px;border:1px solid #c9ced6;border-radius:4px;color:var(--ink)}
.mask-t,.to-sheet{font:inherit;font-size:14px;border:1px solid #c9ced6;background:#fff;color:var(--sumi);padding:5px 10px;border-radius:4px;cursor:pointer;text-decoration:none;white-space:nowrap}
.mask-t[aria-pressed=true]{background:var(--navy);border-color:var(--navy);color:#fff}
.to-sheet{margin-left:auto}
.sheet{padding:18px 0 10px}
.sheet h2,.list h2{font-family:var(--serif);font-size:20px;color:var(--navy-ink);margin:0 0 4px}
.sheet-tip{margin:0 0 12px;font-size:13px;color:var(--muted)}
.bubbles{list-style:none;margin:0;padding:12px 10px;columns:170px;column-gap:14px;column-rule:1px solid var(--gold-soft);background:var(--gold-wash);border:1px solid var(--gold-soft)}
.bubbles li{break-inside:avoid}
.bubbles a{display:flex;align-items:center;gap:8px;padding:4px 4px;text-decoration:none;color:var(--ink);border-radius:3px}
.bubbles a:hover{background:#fff}
.bubbles .n{font-family:var(--serif);font-weight:700;min-width:3.3em;text-align:right;font-size:15px;color:var(--navy-ink)}
.bub{display:flex;gap:5px}
.bub .b{font-style:normal;width:22px;height:22px;border:1.5px solid #b45a52;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:700;color:#b45a52;font-family:var(--sans);line-height:1}
.bub .b.on{background:var(--ink);border-color:var(--ink);color:#fff}
.list{padding-top:18px}
.q{display:grid;grid-template-columns:64px 1fr;gap:0 14px;padding:18px 0;border-top:1px solid var(--line)}
.qn{display:flex;flex-direction:column;align-items:flex-end;gap:4px;padding-top:2px}
.num{font-family:var(--serif);font-weight:900;font-size:30px;line-height:1;color:var(--navy-ink)}
.tag{font-size:12px;color:var(--gold);border:1px solid var(--gold-soft);padding:0 6px;border-radius:2px;white-space:nowrap}
.qb{min-width:0}
.qh{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin-bottom:6px}
.mark{display:inline-flex;align-items:center;justify-content:center;width:38px;height:38px;border:2.5px solid var(--red);border-radius:50%;color:var(--red);font-family:"Times New Roman",var(--serif);font-weight:700;font-size:21px;line-height:1;transform:rotate(-6deg);flex:0 0 auto;cursor:default}
.meta{display:flex;gap:10px;flex-wrap:wrap;font-size:13px;color:var(--muted)}
.meta .src{color:var(--sumi);background:var(--band);padding:1px 8px;border-radius:2px}
.jx{color:var(--ink);font-size:16.5px;line-height:1.85;max-width:40em}
.jx p{margin:0 0 6px}
.jx sub,.jx sup{font-size:.68em;line-height:0}
.jx-img .zoom{display:block;padding:0;margin:4px 0;border:1px solid var(--line);background:#fff;cursor:zoom-in;max-width:100%}
.jx-img .crop{width:100%;max-width:720px}
.jx-h{margin:8px 0 2px;font-size:13px;color:var(--gold)}
.note{margin:0 0 8px;font-size:14px;color:#7a5b16;background:var(--gold-wash);border-left:3px solid var(--gold);padding:6px 10px}
.shared{margin:2px 0 6px;font-size:14px;color:var(--sumi)}
details.stem{margin-top:8px}
details.stem summary{display:inline-flex;align-items:center;gap:6px;cursor:pointer;font-size:14px;color:var(--navy-2);padding:3px 0;list-style:none;user-select:none}
details.stem summary::-webkit-details-marker{display:none}
details.stem summary::before{content:"";width:7px;height:7px;border-right:2px solid currentColor;border-bottom:2px solid currentColor;transform:rotate(-45deg);transition:transform .15s}
details.stem[open] summary::before{transform:rotate(45deg) translate(-1px,-1px)}
details.stem .crop{margin-top:6px;border:1px solid var(--line);max-width:100%;width:720px}
.grp .sub{padding:12px 0 4px;border-top:1px dashed var(--line);margin-top:10px}
.grp .sub:first-of-type{border-top:0}
.subn{font-family:var(--serif);font-weight:700;font-size:18px;color:var(--navy-ink)}
.gstem{margin:0 0 4px}
.psg .psg-h{font-family:var(--serif);font-size:17px;margin:2px 0 4px;color:var(--navy-ink)}
:target{animation:hl 1.6s ease-out}
@keyframes hl{0%{background:var(--gold-wash)}100%{background:transparent}}
/* masked answers */
body.masked .bub .b.on{background:transparent;color:#b45a52;border-color:#b45a52}
body.masked .bubbles li.show .b.on{background:var(--ink);border-color:var(--ink);color:#fff}
body.masked .mark .mk{visibility:hidden}
body.masked .mark{cursor:pointer;border-style:dashed}
body.masked .mark.show .mk{visibility:visible}
body.masked .mark.show{border-style:solid}
body.masked .jx,body.masked .jx-img,body.masked .jx-h{filter:blur(6px);pointer-events:none;user-select:none}
body.masked .qb.show .jx,body.masked .qb.show .jx-img,body.masked .sub.show .jx,body.masked .sub.show .jx-img,body.masked .qb.show .jx-h{filter:none;pointer-events:auto}
.pager{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:28px 0 0}
.pager a{display:flex;flex-direction:column;padding:12px 14px;border:1px solid var(--line);text-decoration:none;color:var(--ink);font-family:var(--serif);font-size:15px}
.pager a small{font-family:var(--sans);font-size:12px;color:var(--gold)}
.pager .next{text-align:right}
.pager a:hover{border-color:var(--gold)}
.site-foot{margin-top:24px;background:#fff}
.foot-note{max-width:1080px;margin:0 auto;padding:0 16px 28px;text-align:center;font-size:12px;color:var(--muted);line-height:1.8}
.foot-note a{color:var(--muted)}
/* lightbox */
.lb{position:fixed;inset:0;background:rgba(19,40,60,.92);z-index:100;display:flex;align-items:center;justify-content:center;padding:12px;overflow:auto}
.lb img{max-width:none;width:min(1600px,220vw);background:#fff}
.lb button{position:fixed;top:10px;right:10px;font:inherit;font-size:15px;background:#fff;border:0;padding:8px 14px;border-radius:4px;cursor:pointer}
@media (min-width:720px){.lb img{width:min(1400px,96vw)}}
@media (max-width:560px){
  main{padding:0 14px 32px}
  .q{grid-template-columns:44px 1fr;gap:0 10px;padding:16px 0}
  .num{font-size:24px}
  .mark{width:34px;height:34px;font-size:19px}
  .bubbles{columns:2;column-gap:6px;padding:8px 4px}
  .volnav a span{display:none}
  .bubbles .n{min-width:2.7em;font-size:14px}
  .bub{gap:3px}
  .bub .b{width:19px;height:19px;font-size:10px}
  .jx{font-size:16px}
  .tools{gap:8px}
  .mask-t,.to-sheet{padding:5px 8px;font-size:13px}
}
@media (max-width:360px){.bub .b{width:17px;height:17px}.bubbles .n{min-width:2.4em}}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}
@media print{.tools,.volnav,.pager,details.stem summary{display:none}.q{break-inside:avoid}}