:root{
  --bg:#f5f3ee; --paper:#fffdf8; --fg:#1a2233; --muted:#5d6577; --faint:#8a90a0; --rule:#d9d4c7;
  --navy:#16284a; --navy-2:#1f3560; --gold:#b5851f; --gold-ink:#8a6414; --gold-soft:#f1e3c2; --red:#b23a2b;
  --on-navy:#f5f3ee; --on-navy-muted:#b9c2d6; --hl:#f6e7b8;
  --display:"Noto Serif TC","Songti TC","PMingLiU",serif;
  --body:"Noto Sans TC","PingFang TC","Microsoft JhengHei",sans-serif;
  --mono:"IBM Plex Mono",ui-monospace,Menlo,monospace;
  --shadow:0 1px 0 rgba(22,40,74,.04),0 8px 24px -12px rgba(22,40,74,.18);
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0f1626; --paper:#152038; --fg:#e8e6df; --muted:#a3abbd; --faint:#7d869b; --rule:#2c3a58;
  --navy:#0a1222; --navy-2:#13203a; --gold:#e0b25a; --gold-ink:#e0b25a; --gold-soft:#3a3220; --red:#ef7f6c;
  --on-navy:#f5f3ee; --on-navy-muted:#9aa6c0; --hl:#5a4718; --shadow:0 8px 24px -12px rgba(0,0,0,.6); color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0f1626; --paper:#152038; --fg:#e8e6df; --muted:#a3abbd; --faint:#7d869b; --rule:#2c3a58;
  --navy:#0a1222; --navy-2:#13203a; --gold:#e0b25a; --gold-ink:#e0b25a; --gold-soft:#3a3220; --red:#ef7f6c;
  --on-navy:#f5f3ee; --on-navy-muted:#9aa6c0; --hl:#5a4718; --shadow:0 8px 24px -12px rgba(0,0,0,.6); color-scheme:dark}
.gb-wrap{max-width:1120px;margin:0 auto;padding-inline:max(20px,env(safe-area-inset-left,0px))}
.gb-bar,.gb-bar *,.pal,.pal *,.gb-foot,.gb-foot *,.gb-pager,.gb-pager *,.gb-toc,.gb-toc *{box-sizing:border-box}
.gb-bar a,.gb-foot a,.pal a,.gb-pager a,.gb-toc a{color:inherit}
.gb-bar,.gb-foot,.pal,.gb-pager,.gb-toc{line-height:1.6}
/* ---------- top bar ---------- */
.gb-bar{position:sticky;top:0;z-index:50;background:color-mix(in srgb,var(--navy) 94%,transparent);backdrop-filter:saturate(1.4) blur(8px);-webkit-backdrop-filter:saturate(1.4) blur(8px);color:var(--on-navy);border-bottom:1px solid rgba(255,255,255,.08)}
.gb-bar .gb-wrap{display:flex;align-items:center;gap:14px;height:56px}
.gb-brand{display:flex;align-items:baseline;gap:10px;text-decoration:none;white-space:nowrap}
.gb-brand b{font-family:var(--display);font-weight:900;font-size:20px;letter-spacing:.06em}
.gb-brand small{font-size:11px;letter-spacing:.3em;color:var(--gold);font-weight:700}
.gb-nav{display:flex;gap:2px;margin-left:auto;align-items:center}
.gb-nav a,.gb-btn{font:500 14px/1 var(--body);color:var(--on-navy-muted);text-decoration:none;padding:9px 11px;border-radius:8px;border:0;background:none;cursor:pointer;white-space:nowrap}
.gb-nav a:hover,.gb-btn:hover{color:var(--on-navy);background:rgba(255,255,255,.07)}
.gb-nav a[aria-current="page"]{color:var(--on-navy);box-shadow:inset 0 -2px 0 var(--gold)}
.gb-search{display:flex;align-items:center;gap:8px;border:1px solid rgba(255,255,255,.16)!important;padding:7px 10px!important}
.gb-search kbd{font:500 11px var(--mono);color:var(--on-navy-muted);border:1px solid rgba(255,255,255,.2);border-radius:4px;padding:1px 5px}
.gb-menu{display:none}
@media (max-width:560px){.gb-brand small{display:none}}
@media (max-width:820px){
  .gb-nav{display:none;position:absolute;top:56px;left:0;right:0;flex-direction:column;align-items:stretch;background:var(--navy);padding:8px 16px 16px;border-bottom:1px solid rgba(255,255,255,.1)}
  .gb-nav.open{display:flex}
  .gb-nav a{padding:12px 8px;font-size:16px}
  .gb-menu{display:inline-flex;margin-left:auto}
  .gb-search kbd{display:none}
}
.gb-ico{width:18px;height:18px;stroke:currentColor;fill:none;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round;flex:none}

.tip{position:fixed;z-index:80;pointer-events:none;background:var(--fg);color:var(--bg);font-size:13px;line-height:1.55;padding:8px 11px;border-radius:8px;max-width:260px;box-shadow:var(--shadow);opacity:0;transition:opacity .1s}
.tip b{font-family:var(--display)}
.tip.on{opacity:1}
mark{background:var(--hl);color:inherit;padding:0 2px;border-radius:3px}
/* command palette */
.pal{position:fixed;inset:0;z-index:100;background:rgba(10,16,30,.55);display:none;align-items:flex-start;justify-content:center;padding:10vh 16px 16px}
.pal.on{display:flex}
.pal .box{width:min(680px,100%);background:var(--paper);color:var(--fg);border-radius:14px;box-shadow:0 30px 80px -20px rgba(0,0,0,.5);overflow:hidden;border:1px solid var(--rule)}
.pal .in{display:flex;align-items:center;gap:10px;padding:0 16px;border-bottom:1px solid var(--rule)}
.pal input{flex:1;border:0;background:transparent;font:18px var(--body);color:var(--fg);outline:none;padding:16px 0;min-width:0}
.pal .list{max-height:60vh;overflow:auto}
.pal .it{display:block;padding:11px 16px;text-decoration:none;border-bottom:1px solid var(--rule)}
.pal .it[aria-selected="true"],.pal .it:hover{background:var(--gold-soft)}
.pal .it .k{font-family:var(--mono);font-size:11px;color:var(--gold-ink);margin-right:8px}
.pal .it b{font-family:var(--display);font-size:16px}
.pal .it div{font-size:13px;color:var(--muted);margin-top:2px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pal .hint{font-size:12px;color:var(--faint);padding:10px 16px}

/* footer */
footer.gb-foot{margin-top:80px;background:var(--navy);color:var(--on-navy-muted);font-size:14px}
footer.gb-foot .gb-wrap{padding-block:36px;display:flex;flex-wrap:wrap;gap:12px 28px;justify-content:space-between}
footer.gb-foot b{font-family:var(--display);color:var(--on-navy);font-size:18px}
footer.gb-foot a{color:var(--on-navy-muted)}

/* chapter page add-ons (namespaced, injected into chapter pages) */
.gb-prog{position:fixed;top:0;left:0;height:3px;background:var(--gold);z-index:60;width:0}
.gb-crumb{font-size:13px;color:var(--on-navy-muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;min-width:0}
.gb-crumb b{color:var(--on-navy);font-weight:500}
@media (max-width:820px){.gb-crumb{display:none}}
.gb-pager{max-width:720px;margin:40px auto 0;padding:0 20px;display:grid;grid-template-columns:1fr 1fr;gap:12px;font-family:var(--body)}
.gb-pager a{display:block;text-decoration:none;background:var(--paper);border:1px solid var(--rule);border-radius:12px;padding:16px 18px;color:var(--fg)}
.gb-pager a:hover{border-color:var(--gold)}
.gb-pager small{display:block;font-size:12px;color:var(--muted);letter-spacing:.1em}
.gb-pager b{font-family:var(--display);font-size:18px;line-height:1.4}
.gb-pager .nx{text-align:right;grid-column:2}
.gb-toc{position:fixed;right:18px;bottom:18px;z-index:55}
.gb-toc button{width:48px;height:48px;border-radius:50%;border:0;background:var(--navy);color:var(--on-navy);box-shadow:var(--shadow);cursor:pointer;display:grid;place-items:center}
.gb-toc .pane{position:absolute;right:0;bottom:58px;width:min(300px,calc(100vw - 36px));background:var(--paper);color:var(--fg);border:1px solid var(--rule);border-radius:12px;box-shadow:var(--shadow);padding:10px;display:none;font-family:var(--body)}
.gb-toc.open .pane{display:block}
.gb-toc .pane a{display:block;text-decoration:none;font-size:14px;line-height:1.5;padding:8px 10px;border-radius:8px}
.gb-toc .pane a:hover,.gb-toc .pane a.on{background:var(--gold-soft)}
.gb-toc .pane .h{font-size:12px;letter-spacing:.2em;color:var(--gold-ink);font-weight:700;padding:6px 10px}
@media print{.gb-bar,.gb-toc,.gb-pager,.gb-prog,footer.gb-foot{display:none!important}}