:root{
  --bg:#0f1216; --bg2:#161b22; --bg3:#1d232c; --line:#2a323d;
  --fg:#e6edf3; --fg2:#a6b2c0; --fg3:#7d8998;
  --accent:#7aa2f7; --accent2:#9d7cd8; --ok:#5ec38a; --warn:#e0a35e; --bad:#e57a7a;
  --r:14px; --tab:62px; --on-accent:#0b0e12;
  --safe-b:env(safe-area-inset-bottom,0px);
  --safe-t:env(safe-area-inset-top,0px);
}
@media (prefers-color-scheme: light){
  :root{
    --bg:#f7f8fa; --bg2:#ffffff; --bg3:#eef1f5; --line:#dde3ea;
    --fg:#141a21; --fg2:#4a5563; --fg3:#6b7684;
    --accent:#2f5fd0; --accent2:#6f42c1; --ok:#1f8a52; --warn:#9a6408; --bad:#b3352f;
    --on-accent:#ffffff;   /* white on #2f5fd0 is 5.6:1; near-black was 3.4:1 */
  }
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;padding:0;background:var(--bg);color:var(--fg)}
body{
  font:16px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",sans-serif;
  overscroll-behavior-y:none; -webkit-text-size-adjust:100%;
}
/* ---------- header ---------- */
header{
  position:sticky; top:0; z-index:20; background:color-mix(in srgb,var(--bg) 96%,transparent);
  backdrop-filter:saturate(160%) blur(12px); border-bottom:1px solid var(--line);
  padding:calc(var(--safe-t) + 10px) 14px 10px; display:flex; align-items:center; gap:10px;
}
/* Long titles get two lines before truncating. */
header h1{font-size:17px;line-height:1.25;margin:0;font-weight:650;letter-spacing:-.01em;flex:1;min-width:0;
  overflow:hidden;display:-webkit-box;-webkit-box-orient:vertical;-webkit-line-clamp:2}
header h1 .math{white-space:nowrap}
.back{background:none;border:0;color:var(--accent);font-size:16px;padding:6px 2px;cursor:pointer}
.iconbtn{background:var(--bg3);border:1px solid var(--line);color:var(--fg2);border-radius:10px;
  padding:7px 10px;font-size:15px;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;
  min-width:38px;min-height:36px;text-decoration:none;flex:none}
main{padding:16px 14px calc(var(--tab) + var(--safe-b) + 28px);max-width:820px;margin:0 auto}
/* Keep the last card clear of the floating install banner. */
body.has-installbar main{padding-bottom:calc(var(--tab) + var(--safe-b) + 118px)}
/* ---------- cards ---------- */
.card{background:var(--bg2);border:1px solid var(--line);border-radius:var(--r);
  padding:14px 15px;margin:0 0 12px;display:block;color:inherit;text-decoration:none}
a.card:active{transform:scale(.99)}
.card h3{margin:0 0 4px;font-size:16px;font-weight:640;letter-spacing:-.01em}
.card h3.ask{font-weight:560;font-size:15.5px;line-height:1.45;letter-spacing:0}
.card p{margin:0;color:var(--fg2);font-size:14.5px}
.eyebrow{font-size:11.5px;text-transform:uppercase;letter-spacing:.09em;color:var(--fg3);
  font-weight:700;margin:22px 0 9px}
.eyebrow:first-child{margin-top:4px}
.lead{color:var(--fg2);font-size:15px;margin:0 0 18px}
.chip{display:inline-block;font-size:11.5px;padding:2px 9px;border-radius:999px;
  background:var(--bg3);color:var(--fg2);border:1px solid var(--line);margin:6px 6px 0 0}
.chip.tech{color:var(--accent);border-color:color-mix(in srgb,var(--accent) 35%,var(--line))}
.chip.warm-up{color:var(--ok)} .chip.core{color:var(--accent)} .chip.advanced{color:var(--accent2)}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.grid .card{margin:0}
@media (max-width:380px){.grid{grid-template-columns:1fr}}
/* ---------- prose ---------- */
.prose p{margin:0 0 12px;color:var(--fg)}
.prose strong{font-weight:660}
code{background:var(--bg3);padding:1px 5px;border-radius:5px;font-size:13.5px;
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace}
.note{border-left:3px solid var(--warn);background:color-mix(in srgb,var(--warn) 9%,transparent);
  padding:10px 12px;border-radius:0 10px 10px 0;margin:0 0 10px;font-size:14.5px;color:var(--fg2)}
.note b{color:var(--warn)}
ul.tight{margin:0 0 12px;padding-left:20px;color:var(--fg2)}
ul.tight li{margin:0 0 7px}
/* ---------- steps ---------- */
.step{border:1px solid var(--line);border-radius:12px;margin:0 0 10px;background:var(--bg2);overflow:hidden}
.step > .sh{display:flex;gap:11px;align-items:flex-start;padding:13px 14px;cursor:pointer}
.num{flex:none;width:24px;height:24px;border-radius:8px;background:var(--bg3);color:var(--accent);
  font-size:12.5px;font-weight:700;display:grid;place-items:center;margin-top:1px}
.sh b{font-weight:620;font-size:15px;flex:1}
.sh .caret{color:var(--fg3);font-size:12px;flex:none;margin-top:4px;transition:transform .18s}
.step.open .caret{transform:rotate(90deg)}
.sbody{padding:0 14px 14px 49px;font-size:15px}
.why{margin-top:10px;padding:10px 12px;border-radius:10px;background:var(--bg3);
  font-size:14px;color:var(--fg2);border-left:3px solid var(--accent2)}
.why b{color:var(--accent2);font-weight:650}
.review-card .review-line{margin:6px 0 0;font-size:14.5px}
.review-card .wrong-line b{color:var(--bad)}
.review-card .right-line b{color:var(--ok)}
/* ---------- math ---------- */
.math,.mathblock{font-family:"Latin Modern Math","Cambria Math",Georgia,"Times New Roman",serif;
  font-size:1.03em}
/* Inline math wraps at spaces so a long expression can never overflow the
   viewport; display math instead scrolls inside its own box. */
.math{white-space:normal}
.mathblock{display:block;text-align:center;margin:14px 0;overflow-x:auto;overflow-y:hidden;
  padding-bottom:4px;font-size:1.06em}
.math i,.mathblock i{font-style:italic;font-family:inherit}
.mu{font-style:normal;font-family:inherit}
.msym{font-style:normal;font-family:inherit}
/* Operators the math fonts often lack (see t() in app.js): use fonts known to have them. */
.mop{font-family:"STIX Two Math","Cambria Math","Segoe UI Symbol",-apple-system,BlinkMacSystemFont,
  "Segoe UI",Roboto,"Helvetica Neue",sans-serif;margin:0 .08em}
.mu sub{font-size:.85em}
.mthin{display:inline-block;width:.17em}.mquad{display:inline-block;width:1em}
.mfrac{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;
  font-size:.86em;margin:0 .18em}
.mnum{border-bottom:1px solid currentColor;padding:0 .3em}
.mden{padding:0 .3em}
.mover{border-top:1px solid currentColor}
.mbinom{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;
  font-size:.84em;line-height:1.15;margin:0 .05em}
sub,sup{font-size:.72em;line-height:0;white-space:nowrap}
/* ---------- forms ---------- */
label.f{display:block;margin:0 0 14px}
label.f > span{display:block;font-size:14px;font-weight:600;margin-bottom:5px}
label.f .hint{font-weight:400;color:var(--fg3);font-size:13px;margin:3px 0 6px;display:block}
input[type=text],textarea{width:100%;background:var(--bg2);border:1px solid var(--line);
  color:var(--fg);border-radius:10px;padding:10px 12px;font-family:inherit;font-size:15px;line-height:1.5;resize:vertical}
input[type=text]:focus,textarea:focus{outline:2px solid color-mix(in srgb,var(--accent) 55%,transparent);
  outline-offset:-1px;border-color:var(--accent)}
.btn{display:inline-block;background:var(--accent);color:var(--on-accent);border:0;border-radius:11px;
  padding:12px 16px;font-family:inherit;font-size:15px;font-weight:600;cursor:pointer;text-align:center}
[hidden]{display:none!important}
.btn.ghost{background:var(--bg3);color:var(--fg);border:1px solid var(--line)}
.btn.wide{width:100%;margin-bottom:10px}
.row{display:flex;gap:9px;margin-bottom:12px}
.row .btn{flex:1}
pre.out{background:var(--bg2);border:1px solid var(--line);border-radius:12px;padding:13px;
  font:12.5px/1.55 ui-monospace,SFMono-Regular,Menlo,monospace;color:var(--fg2);
  white-space:pre-wrap;overflow-wrap:anywhere;margin:0 0 12px}
/* ---------- drills ---------- */
.opt{display:block;width:100%;text-align:left;background:var(--bg2);border:1px solid var(--line);
  color:var(--fg);border-radius:11px;padding:12px 14px;margin:0 0 9px;font-family:inherit;font-size:15px;line-height:1.5;cursor:pointer}
.opt.right{border-color:var(--ok);background:color-mix(in srgb,var(--ok) 13%,var(--bg2))}
.opt.wrong{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 13%,var(--bg2))}
.opt[disabled]{cursor:default}
.progress{height:4px;background:var(--bg3);border-radius:999px;overflow:hidden;margin:0 0 16px}
.progress i{display:block;height:100%;background:var(--accent);transition:width .3s}
.score{font-size:13px;color:var(--fg3);margin:0 0 14px}
/* ---------- checklist ---------- */
.chk{display:flex;gap:11px;align-items:flex-start;padding:11px 13px;background:var(--bg2);
  border:1px solid var(--line);border-radius:11px;margin:0 0 8px;cursor:pointer;font-size:14.5px}
.chk input{margin:3px 0 0;flex:none;width:18px;height:18px;accent-color:var(--accent)}
.chk.done{opacity:.55}
.chk.done span{text-decoration:line-through}
/* ---------- tabbar ---------- */
nav.tabs{position:fixed;bottom:0;left:0;right:0;z-index:30;display:flex;
  background:color-mix(in srgb,var(--bg) 97%,transparent);backdrop-filter:blur(16px);
  border-top:1px solid var(--line);padding-bottom:var(--safe-b)}
nav.tabs a{flex:1;min-width:0;padding:8px 1px 7px;text-align:center;text-decoration:none;
  color:var(--fg3);font-size:11.5px;font-weight:600;letter-spacing:.01em;
  white-space:nowrap;overflow:hidden;text-overflow:clip}
nav.tabs a .ic{display:block;font-size:19px;line-height:1.25;margin-bottom:1px}
nav.tabs a.on{color:var(--accent)}
/* ---------- install ---------- */
ol.steps{margin:0 0 16px;padding-left:22px;color:var(--fg2)}
ol.steps li{margin:0 0 9px;padding-left:2px}
ol.steps b{color:var(--fg);font-weight:620}
.installbar{position:fixed;left:10px;right:10px;bottom:calc(var(--tab) + var(--safe-b) + 10px);
  z-index:40;display:flex;gap:10px;align-items:center;background:var(--bg3);
  border:1px solid var(--line);border-radius:14px;padding:11px 12px;
  box-shadow:0 8px 28px rgba(0,0,0,.34);animation:ibup .28s ease-out}
@keyframes ibup{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
.ib-text{flex:1;min-width:0;font-size:13px;line-height:1.42;color:var(--fg2)}
.ib-text b{display:block;color:var(--fg);font-size:14px;font-weight:640;margin-bottom:1px}
.ib-text span b{display:inline;font-size:inherit}
.ib-acts{flex:none;display:flex;align-items:center;gap:6px}
.ib-more{color:var(--accent);text-decoration:none;font-size:13.5px;font-weight:600;padding:6px 4px}
.ib-x{background:none;border:0;color:var(--fg3);font-size:22px;line-height:1;padding:2px 6px;cursor:pointer}
.empty{color:var(--fg3);text-align:center;padding:40px 10px;font-size:15px}
.kbd{font-size:12.5px;color:var(--fg3);margin-top:18px;text-align:center}

/* ---------- plain-English layer ---------- */
/* Every dense page opens with this: the same claim without the machinery.
   Deliberately quiet — it sits above the formal statement, not instead of it. */
.plain{border-left:3px solid var(--ok);background:color-mix(in srgb,var(--ok) 9%,transparent);
  padding:12px 14px;border-radius:0 12px 12px 0;margin:0 0 14px;font-size:15px;color:var(--fg)}
.plain b{display:block;color:var(--ok);font-size:11.5px;text-transform:uppercase;
  letter-spacing:.09em;font-weight:700;margin-bottom:5px}
.pre{font-size:13.5px;color:var(--fg3);margin:-4px 0 16px;line-height:1.5}
.pre b{color:var(--fg2);font-weight:600}
.pre a{color:var(--accent);text-decoration:none}
/* ---------- primer ---------- */
.card.hero{border-color:color-mix(in srgb,var(--accent) 45%,var(--line));
  background:color-mix(in srgb,var(--accent) 8%,var(--bg2))}
.card.hero h3{color:var(--accent)}
.chip.ok{color:var(--ok);border-color:color-mix(in srgb,var(--ok) 35%,var(--line))}
.lead.sm{font-size:14px;margin:-4px 0 12px}
.card.lesson h3{display:flex;gap:9px;align-items:baseline}
.card.lesson .tick{flex:none;color:var(--fg3);font-size:13px}
.card.lesson.read .tick{color:var(--ok)}
.card.lesson.read h3{color:var(--fg2)}
.card.slim h3{margin:0;color:var(--accent);font-weight:600;font-size:15px}
.card.step-card h3{display:flex;gap:10px;align-items:flex-start;line-height:1.4}
.card.step-card .num{margin-top:0}
.card.step-card.read{border-color:color-mix(in srgb,var(--ok) 35%,var(--line))}
.card.worked{background:var(--bg3)}
.card.worked h3{margin-bottom:8px}
.card.worked .prose p:last-child{margin-bottom:0}
/* Symbol/plain-reading pairs, in the lessons and the notation page. */
dl.jargon{margin:0 0 14px;padding:0}
dl.jargon dt{font-size:15px;font-weight:600;margin:0 0 2px}
dl.jargon dd{margin:0 0 11px;padding:0 0 0 14px;border-left:2px solid var(--line);
  color:var(--fg2);font-size:14.5px}
dl.jargon.sym dd b{display:block;color:var(--fg);font-weight:600;margin-bottom:1px}
/* Check-yourself questions: the answer stays hidden until asked for. */
.qa{background:var(--bg2);border:1px solid var(--line);border-radius:12px;padding:13px 14px;
  margin:0 0 10px}
.qa .qq{margin:0 0 10px;font-size:15px}
.btn.sm{padding:7px 12px;font-size:13.5px;border-radius:9px}
.qans{margin-top:11px;padding:11px 12px;border-radius:10px;background:var(--bg3);
  font-size:14.5px;color:var(--fg2);border-left:3px solid var(--ok)}
.row.nav{margin-top:18px}
.row.nav .btn{margin-bottom:0;text-decoration:none;line-height:1.4}
/* ---------- course (B&R) ---------- */
/* Tab bar tightens slightly at phone widths so 7 labels fit. */
@media (max-width:390px){nav.tabs a{font-size:11px;padding:8px 0 7px}}
@media (max-width:340px){nav.tabs a{font-size:10.5px;letter-spacing:0}}
/* Chapter map cards */
.chapter-card h3{display:flex;align-items:baseline;gap:10px;margin-bottom:5px}
.ch-num{flex:none;font-size:11px;font-weight:700;color:var(--accent2);background:color-mix(in srgb,var(--accent2) 12%,var(--bg3));
  border-radius:999px;padding:1px 8px;letter-spacing:.03em}
.ch-num.sm{font-size:10px}
.chapter-card.visited{border-color:color-mix(in srgb,var(--ok) 30%,var(--line))}
.locked-card{background:var(--bg2);border:1px solid var(--line);border-radius:var(--r);padding:12px 14px;opacity:.6}
.locked-card h3{margin:4px 0 3px;font-size:15px;font-weight:600}
.locked-card p{margin:0;color:var(--fg3);font-size:13.5px}
/* Section headings within a chapter */
h2.sec-heading{font-size:18px;font-weight:680;letter-spacing:-.02em;margin:32px 0 12px;
  border-top:1px solid var(--line);padding-top:24px;color:var(--fg)}
h2.sec-heading:first-of-type{border-top:0;padding-top:0;margin-top:8px}
/* SVG figures (animations and diagrams) */
.anim-fig{margin:16px 0 20px;background:var(--bg2);border:1px solid var(--line);border-radius:var(--r);overflow:hidden}
.anim-fig svg{max-width:100%;display:block;margin:0 auto;padding:14px 10px 6px}
@media (prefers-reduced-motion:reduce){.anim-fig *{animation:none!important}}
.anim-fig figcaption{font-size:14px;color:var(--fg2);padding:6px 14px 12px;line-height:1.45;margin:0}
/* Inline section quiz */
.cq-block{background:var(--bg2);border:1px solid var(--line);border-radius:12px;padding:14px;margin:14px 0}
.cq-q{margin:0 0 12px;font-size:15px;font-weight:560}
.cq-opt{display:block;width:100%;text-align:left;background:var(--bg3);border:1px solid var(--line);
  color:var(--fg);border-radius:9px;padding:10px 13px;margin:0 0 8px;font-family:inherit;font-size:14.5px;line-height:1.45;cursor:pointer}
.cq-opt.right{border-color:var(--ok);background:color-mix(in srgb,var(--ok) 13%,var(--bg2))}
.cq-opt.wrong{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 11%,var(--bg2))}
.cq-opt[disabled]{cursor:default}
.cq-why{margin-top:10px;padding:10px 12px;border-radius:9px;background:var(--bg3);
  font-size:14px;color:var(--fg2);border-left:3px solid var(--accent)}
/* Mastery quiz */
.ch-divider{height:1px;background:var(--line);margin:36px 0 24px}
.cq-saved{font-size:14px;color:var(--ok);margin:-6px 0 14px;font-weight:600}

/* ---------- interactive widgets (js/widgets.js) ---------- */
/* Filled highlights: the light theme's --ok/--warn are too light for small text on top. */
:root{--wg-ok-fill:#5ec38a;--wg-ok-ink:#0b0e12;--wg-warn-fill:#e0a35e;--wg-warn-ink:#0b0e12}
@media (prefers-color-scheme: light){:root{--wg-ok-fill:#17703f;--wg-ok-ink:#ffffff;--wg-warn-fill:#8a5a07;--wg-warn-ink:#ffffff}}
.wg{margin:16px 0 20px;background:var(--bg2);border:1px solid color-mix(in srgb,var(--accent) 35%,var(--line));
  border-radius:var(--r);padding:13px 14px 6px;font-size:14.5px}
.wg p{margin:0 0 10px}
.wg-h{font-weight:650;font-size:15px;margin:0 0 11px;display:flex;align-items:center;gap:9px}
.wg-h2{font-weight:640;font-size:14.5px;margin:4px 0 8px}
.wg-tag{font-size:10.5px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:var(--on-accent);
  background:var(--accent);border-radius:6px;padding:2px 7px}
.wg-in{display:flex;flex-wrap:wrap;align-items:flex-end;gap:8px 12px;margin:0 0 10px}
.wg-f{display:flex;align-items:center;gap:6px;font-size:14px;color:var(--fg2)}
.wg-f input,.wg-f select{width:4.6em;background:var(--bg);border:1px solid var(--line);color:var(--fg);
  border-radius:9px;padding:7px 9px;font:15px/1.3 ui-monospace,SFMono-Regular,Menlo,monospace}
.wg-f select{width:auto;font-family:inherit}
.wg-f input.bad{border-color:var(--bad);outline:1px solid var(--bad)}
.wg-lbl{font-size:14px;color:var(--fg2);margin-right:6px;align-self:center}
.wg-btns{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 10px}
.wg .btn.sm{min-height:44px}
.wg .btn.sm[disabled]{opacity:.45;cursor:default}
.wg-seg{display:flex;border:1px solid var(--line);border-radius:10px;overflow:hidden;margin:0 0 10px;width:max-content;max-width:100%}
.wg-seg button{background:var(--bg3);color:var(--fg2);border:0;border-right:1px solid var(--line);padding:8px 13px;
  font-family:inherit;font-size:14px;font-weight:600;cursor:pointer;min-height:40px}
.wg-seg button:last-child{border-right:0}
.wg-seg button.on{background:var(--accent);color:var(--on-accent)}
.wg-big{font-size:17px;margin:4px 0 10px}
.wg-dim{color:var(--fg3);font-size:13.5px}
.wg-ok{color:var(--ok)} .wg-bad{color:var(--bad)} .wg-warn{color:var(--warn)}
.wg-mono{font:13px/1.6 ui-monospace,SFMono-Regular,Menlo,monospace;color:var(--fg2);overflow-wrap:anywhere}
.wg-scroll{overflow-x:auto;margin:0 0 10px;-webkit-overflow-scrolling:touch}
.wg-tall{max-height:300px;overflow-y:auto}
table.wg-t{border-collapse:collapse;font-size:13.5px;min-width:100%;margin:0 0 10px}
.wg-scroll table.wg-t{margin:0}
.wg-t th,.wg-t td{padding:5px 8px;border-bottom:1px solid var(--line);text-align:left;white-space:nowrap}
.wg-t th{color:var(--fg3);font-weight:600;font-size:12px}
.wg-t tr.dim td{opacity:.45}
.wg-t tr.hi td{background:color-mix(in srgb,var(--ok) 11%,transparent)}
.wg-bit{font:700 14px ui-monospace,Menlo,monospace;text-align:center!important}
.wg-bit.b1{color:var(--accent)} .wg-bit.b0{color:var(--fg3)}
.wg-crt td,.wg-crt th{text-align:center!important;min-width:2.1em}
.wg-crt td.tgt{background:var(--wg-ok-fill);color:var(--wg-ok-ink);font-weight:700}
.wg-crt td.clash{background:color-mix(in srgb,var(--bad) 22%,transparent)}
.wg-crt td.new{background:color-mix(in srgb,var(--accent) 30%,transparent)}
.wg-grid{display:flex;flex-wrap:wrap;gap:5px;margin:0 0 12px}
.wg-cell{min-width:44px;height:44px;padding:0 4px;border-radius:9px;border:1px solid var(--line);background:var(--bg3);
  color:var(--fg2);font:600 14px ui-monospace,Menlo,monospace;cursor:pointer;position:relative;line-height:1.1}
.wg-cell small{display:block;font-size:11px;font-weight:600}
.wg-cell.u{color:var(--fg);border-color:color-mix(in srgb,var(--accent) 55%,var(--line));
  background:color-mix(in srgb,var(--accent) 14%,var(--bg3))}
.wg-cell.sel{background:var(--accent);color:var(--on-accent);border-color:var(--accent)}
.wg-cell.pair{background:var(--ok);color:#0b0e12;border-color:var(--ok)}
.wg-chips{display:flex;flex-wrap:wrap;align-items:center;gap:4px 2px;margin:0 0 12px}
.wg-chip{display:inline-flex;flex-direction:column;align-items:center;min-width:30px;padding:3px 6px;border-radius:8px;
  background:var(--bg3);border:1px solid var(--line);font:600 14px ui-monospace,Menlo,monospace}
.wg-chip sup{font-size:9.5px;font-weight:500;color:var(--fg3);line-height:1.2}
.wg-chip.one{border-color:var(--ok);color:var(--ok)}
.wg-chip.rep{border-style:dashed;opacity:.65}
.wg-arr{color:var(--fg3);font-size:12px}
.wg-fig svg{display:block;max-width:260px;width:100%;margin:0 auto 10px}
.wg-ring .track{fill:none;stroke:var(--line);stroke-width:1.5}
.wg-ring .chord{stroke:var(--accent);stroke-opacity:.55;stroke-width:1.5}
.wg-ring .node circle{fill:var(--bg3);stroke:var(--line);transition:fill .12s}
.wg-ring .node text{fill:var(--fg2);font-family:ui-monospace,Menlo,monospace;font-weight:600}
.wg-ring .node.a circle{fill:var(--accent);stroke:var(--accent)}
.wg-ring .node.r circle{fill:var(--wg-ok-fill);stroke:var(--wg-ok-fill)}
.wg-ring .node.cur circle{fill:var(--wg-warn-fill);stroke:var(--wg-warn-fill)}
.wg-ring .node.a text{fill:var(--on-accent)}
.wg-ring .node.r text{fill:var(--wg-ok-ink)}
.wg-ring .node.cur text{fill:var(--wg-warn-ink)}
.wg-sub{border-top:1px solid var(--line);margin-top:6px;padding-top:10px}
.wg-streak{font-size:13px;color:var(--fg3);align-self:center;margin-left:auto}
.wg-streak b{color:var(--fg)}
ol.wg-steps{margin:0 0 12px;padding-left:20px;color:var(--fg2)}
ol.wg-steps li{margin:0 0 6px}
.wg ul.tight{color:var(--fg)}
.wg-t .math{white-space:nowrap}
/* Text size (Start page). zoom reflows the content column; header and tabs stay put. */
body.ts-lg main{zoom:1.12}
body.ts-xl main{zoom:1.25}
.row.seg .btn{margin-bottom:0;padding:8px 0;line-height:1.2;min-height:44px}
.row.seg .btn.on{border-color:var(--accent);color:var(--accent);background:color-mix(in srgb,var(--accent) 12%,var(--bg2))}
.book-ref{margin:-6px 0 16px;font-size:13.5px;color:var(--fg3)}
.book-ref b{color:var(--fg2);font-weight:620}
.wg-pair{display:inline-flex;align-items:center;gap:4px;white-space:nowrap}
.wg-cell.mem{outline:3px solid var(--ok);outline-offset:-3px;color:var(--fg)}
.wg-ring .node text{fill:var(--fg)}
details.deeper{border-left:3px solid var(--line);padding:2px 0 2px 12px;margin:0 0 12px}
details.deeper summary{cursor:pointer;color:var(--accent);font-weight:600;font-size:14px;padding:6px 0;min-height:32px}
details.deeper[open] summary{margin-bottom:6px}
/* Chapter navigation: section index, "section x of y", see-also lists, resume card. */
.toc{margin:4px 0 18px;border:1px solid var(--line);border-radius:var(--r);background:var(--bg2);padding:10px 14px}
.toc summary{cursor:pointer;font-weight:620;font-size:15px}
.toc ol{margin:8px 0 2px;padding-left:22px;font-size:15px}
.toc li{margin:4px 0}
.toc a{color:var(--accent);text-decoration:none}
.ch-sec{border-top:1px solid var(--line);margin-top:28px}
.sec-of{margin-top:22px;font-size:12px;font-weight:650;letter-spacing:.05em;text-transform:uppercase;color:var(--fg3)}
.ch-sec h2.sec-heading{margin-top:2px;border-top:0;padding-top:0}
ul.see{list-style:none;margin:6px 0 16px;padding:0}
ul.see li{margin:0 0 6px}
ul.see a{display:block;padding:9px 12px;border:1px solid var(--line);border-radius:10px;background:var(--bg2);
  color:var(--fg);text-decoration:none;font-size:15px}
.see-k{display:block;font-size:11.5px;font-weight:650;letter-spacing:.04em;text-transform:uppercase;color:var(--accent2)}
.card.resume{border-color:var(--accent)}