/* routing.jelia.nyc — shared design system (engine from waves.jelia.nyc, via fractals).
   Palette 2026-10-22: "route map" — cobalt for the chosen path, amber for ordinary traffic,
   plum/rose for trouble, teal as a third trace. Picked so the three meanings stay apart under
   simulated protan/deutan/tritan vision (worst pair dE about 19 light / 22 dark), and muted text
   is kept near-black / near-white because J reads with low vision. Change a token here, not in a chapter. */

:root{
  --bg:#F3F1EA; --panel:#FFFFFF; --ink:#14161C; --muted:#2C2E33; --line:#CFCBBF;
  --accent:#1F4FD1; --wave:#9A5B00; --warn:#A0108F; --soft:#F8F6F0;
  /* extra series colours for multi-line canvases (E field, B field, third trace) */
  --efield:#1F4FD1; --bfield:#9A5B00; --third:#00766E;
  --f-display:"Bricolage Grotesque","Segoe UI",system-ui,sans-serif;
  --f-body:"IBM Plex Sans","Segoe UI",system-ui,sans-serif;
  --f-mono:"IBM Plex Mono",ui-monospace,Menlo,Consolas,monospace;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0C0F17; --panel:#131826; --ink:#F1F3F8; --muted:#DCE1EC; --line:#2B3347;
  --accent:#7FA6FF; --wave:#F2B544; --warn:#FF5C8A; --soft:#182035;
  --efield:#7FA6FF; --bfield:#F2B544; --third:#3DD6C3; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0C0F17; --panel:#131826; --ink:#F1F3F8; --muted:#DCE1EC; --line:#2B3347;
  --accent:#7FA6FF; --wave:#F2B544; --warn:#FF5C8A; --soft:#182035;
  --efield:#7FA6FF; --bfield:#F2B544; --third:#3DD6C3; color-scheme:dark}

*{box-sizing:border-box}
html{scroll-padding-top:72px}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 var(--f-body);padding:0 16px}
img{max-width:100%}
a{color:var(--wave);text-underline-offset:2px}
[hidden]{display:none!important}

.wrap{max-width:980px;margin:0 auto;padding-block:40px 64px;display:grid;gap:56px}
h1,h2,h3{font-family:var(--f-display);text-wrap:balance;margin:0;line-height:1.1}
h1{font-size:clamp(2.6rem,7vw,4.6rem);font-weight:800;letter-spacing:-.02em}
h1 em,h2 em{font-style:normal;color:var(--accent)}
h2{font-size:clamp(1.5rem,3.4vw,2.1rem);font-weight:700}
h3{font-size:1.2rem;font-weight:700}
p{margin:0;max-width:65ch}
ul,ol{margin:0;padding-left:1.3em;max-width:65ch;display:grid;gap:6px}
.eyebrow{font:500 .75rem/1 var(--f-mono);letter-spacing:.12em;text-transform:uppercase;color:var(--muted)}
.mono{font-family:var(--f-mono)}
section{display:grid;gap:18px}
.prose{display:grid;gap:14px}
.lede{font-size:1.12rem;color:var(--muted)}
.facts{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1px;background:var(--line);border:1px solid var(--line);border-radius:6px;overflow:hidden}
.facts div{background:var(--panel);padding:16px 18px;display:grid;gap:4px}
.facts b{font:600 1.5rem/1.2 var(--f-mono);font-variant-numeric:tabular-nums}
.facts span{color:var(--muted);font-size:.9rem}
.note{border-left:3px solid var(--accent);padding:12px 16px;background:var(--panel);border-radius:0 6px 6px 0;max-width:none}
.note strong{color:var(--accent)}

/* equation block: the one formula a section hangs on, set big, with a plain-English gloss */
.eq{background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:16px 20px;display:grid;gap:6px}
.eq .f{font:600 clamp(1.1rem,3vw,1.5rem)/1.3 var(--f-mono);overflow-wrap:anywhere}
.eq .g{color:var(--muted);font-size:.95rem}

/* "go deeper" — optional maths and detail, collapsed so the main read stays light */
details.deep{background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:0 18px}
details.deep>summary{cursor:pointer;padding:14px 0;font:600 .9rem var(--f-mono);color:var(--wave);list-style:none}
details.deep>summary::before{content:"+ ";}
details.deep[open]>summary::before{content:"− ";}
details.deep>div{padding:0 0 18px;display:grid;gap:12px}

/* player (narrated walkthrough) — same look as the 2.4 GHz original */
.player{background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:14px;display:grid;gap:12px}
.screen{position:relative;aspect-ratio:16/9;max-width:100%;background:var(--soft);border-radius:4px;overflow:hidden}
.screen canvas{position:absolute;inset:0;width:100%;height:100%}
.bigplay{position:absolute;right:16px;bottom:16px;font:600 .95rem var(--f-body);background:var(--accent);color:#fff;border:0;border-radius:999px;padding:10px 18px;cursor:pointer}
/* phones: the play pill would sit on top of the scene's corner labels, so shrink it */
@media (max-width:560px){.bigplay{right:8px;bottom:8px;padding:6px 12px;font-size:.8rem;opacity:.92}}
.caption{min-height:3.4em;font-size:1.05rem;padding:2px 4px}
.controls{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.btn{font:600 .9rem var(--f-body);background:var(--ink);color:var(--panel);border:0;border-radius:4px;padding:8px 14px;cursor:pointer;min-width:5.5em}
.track{flex:1 1 200px;height:10px;background:var(--soft);border:1px solid var(--line);border-radius:5px;position:relative;cursor:pointer}
.track .fill{position:absolute;inset:0 auto 0 0;background:var(--accent);border-radius:5px}
.track i{position:absolute;top:-3px;bottom:-3px;width:1px;background:var(--muted);opacity:.5}
.time{font:500 .85rem var(--f-mono);color:var(--muted);font-variant-numeric:tabular-nums}
.voice{display:flex;align-items:center;gap:6px;font-size:.9rem;color:var(--muted)}
.chapters{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:6px;max-width:none}
.chapters button{width:100%;text-align:left;font:500 .85rem var(--f-body);color:var(--ink);background:transparent;border:1px solid var(--line);border-radius:4px;padding:8px 10px;cursor:pointer;display:grid;gap:2px}
.chapters button small{font:500 .7rem var(--f-mono);color:var(--muted);letter-spacing:.08em}
.chapters button[aria-current="true"]{border-color:var(--accent);background:var(--soft)}
button:focus-visible,input:focus-visible,select:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* lab instruments */
.lab{background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:18px;display:grid;gap:16px}
.lab canvas{width:100%;height:260px;display:block;touch-action:none}
.lab canvas.tall{height:360px}
.lab canvas.short{height:190px}
input[type=range]{width:100%;accent-color:var(--accent)}
.ctl{display:grid;gap:4px}
.ctl label{font:500 .78rem var(--f-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--muted);display:flex;justify-content:space-between;gap:8px}
.ctl label b{color:var(--ink);font-weight:600;text-transform:none;letter-spacing:0}
.ctlgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px}
.presets{display:flex;flex-wrap:wrap;gap:6px}
.chip{font:500 .8rem var(--f-body);background:var(--soft);color:var(--ink);border:1px solid var(--line);border-radius:999px;padding:5px 12px;cursor:pointer}
.chip[aria-pressed="true"]{border-color:var(--accent);color:var(--accent)}
.readout{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:14px}
.readout div{display:grid;gap:2px;min-width:0}
.readout b{font:600 1.15rem/1.3 var(--f-mono);font-variant-numeric:tabular-nums;overflow-wrap:anywhere}
.readout span{font-size:.78rem;color:var(--muted);text-transform:uppercase;letter-spacing:.08em;font-family:var(--f-mono)}
.hint{font-size:.85rem;color:var(--muted)}

/* table + glossary */
.tablewrap{overflow-x:auto;border:1px solid var(--line);border-radius:8px;background:var(--panel)}
table{border-collapse:collapse;width:100%;min-width:620px;font-size:.95rem}
th,td{text-align:left;padding:12px 14px;border-bottom:1px solid var(--line);vertical-align:top}
th{font:600 .75rem var(--f-mono);letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
tr:last-child td{border-bottom:0}
td:first-child{font:600 1rem var(--f-mono);white-space:nowrap}
tr.hl td:first-child{color:var(--accent)}
dl{display:grid;grid-template-columns:minmax(120px,max-content) 1fr;gap:10px 22px;margin:0}
dt{font:600 .95rem var(--f-mono)}
dd{margin:0;color:var(--muted);max-width:60ch}
@media (max-width:560px){dl{grid-template-columns:1fr;gap:2px}dd{margin-bottom:10px}}
footer{color:var(--muted);font-size:.85rem}

/* site chrome: top bar + prev/next pager, rendered by site.js from one chapter list */
.topbar{position:sticky;top:0;z-index:5;margin:0 -16px;padding:10px 16px;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.topbar .in{max-width:980px;margin:0 auto;display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.topbar .brand{font:800 1.05rem var(--f-display);color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:8px}
.topbar .brand svg{color:var(--accent)}
.topbar .where{font:500 .75rem var(--f-mono);letter-spacing:.08em;text-transform:uppercase;color:var(--muted);flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.topbar select{font:500 .85rem var(--f-body);background:var(--panel);color:var(--ink);border:1px solid var(--line);border-radius:4px;padding:6px 8px;max-width:100%}
.themebtn{font:500 .8rem var(--f-mono);background:transparent;color:var(--muted);border:1px solid var(--line);border-radius:4px;padding:6px 10px;cursor:pointer}
.pager{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.pager a{display:grid;gap:4px;padding:14px 16px;border:1px solid var(--line);border-radius:8px;background:var(--panel);text-decoration:none;color:var(--ink)}
.pager a small{font:500 .7rem var(--f-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}
.pager a b{font:700 1.05rem var(--f-display)}
.pager a.next{text-align:right;grid-column:2}
@media (max-width:560px){.pager{grid-template-columns:1fr}.pager a.next{grid-column:1}}

/* hub: chapter cards */
.parts{display:grid;gap:36px}
.part{display:grid;gap:14px}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:12px}
.card{display:grid;gap:8px;align-content:start;padding:18px;border:1px solid var(--line);border-radius:8px;background:var(--panel);text-decoration:none;color:var(--ink);transition:border-color .18s,transform .18s,background-color .18s,box-shadow .18s}
.card:hover,.card:focus-visible{border-color:var(--accent);transform:translateY(-2px);background:color-mix(in srgb,var(--panel) 86%,var(--accent));box-shadow:0 6px 18px color-mix(in srgb,var(--accent) 18%,transparent)}
.card:hover b,.card:focus-visible b{color:var(--accent)}
.card small{font:500 .7rem var(--f-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}
.card b{font:700 1.25rem/1.15 var(--f-display)}
.card span{color:var(--muted);font-size:.93rem}
.card.star{border-color:var(--accent)}

/* hub flair (J 2026-10-06): tiles take the neon of J's logo, one colour per part, glowing edge + tinted hover */
.part{--pc:var(--accent)}
.part:nth-child(1){--pc:#3D7BFF}.part:nth-child(2){--pc:#1FB5A3}.part:nth-child(3){--pc:#E0A030}
.part:nth-child(4){--pc:#D9488F}.part:nth-child(5){--pc:#8A6CFF}
.part>.eyebrow{color:var(--pc)}
.part .card{position:relative;overflow:hidden;border-color:color-mix(in srgb,var(--pc) 35%,var(--line))}
.part .card::before{content:"";position:absolute;inset:0 0 auto 0;height:3px;background:var(--pc);box-shadow:0 0 12px var(--pc)}
.part:nth-child(4) .card::before,.part:nth-child(5) .card::before{background:linear-gradient(90deg,#3D7BFF,#1FB5A3,#E0A030,#D9488F)}
.part .card:hover,.part .card:focus-visible{border-color:var(--pc);background:color-mix(in srgb,var(--panel) 86%,var(--pc));
  box-shadow:0 6px 20px color-mix(in srgb,var(--pc) 28%,transparent)}
.part .card:hover b,.part .card:focus-visible b{color:var(--pc)}
.part .card small{color:color-mix(in srgb,var(--pc) 70%,var(--muted))}
/* the contents heading gets the logo's run as a neon underline */
.neon-rule{height:3px;border-radius:3px;max-width:420px;background:linear-gradient(90deg,#3D7BFF,#1FB5A3,#E0A030,#D9488F);box-shadow:0 0 10px rgba(61,123,255,.35)}
@media (prefers-color-scheme:light){:root:not([data-theme="dark"]) .part:nth-child(5){--pc:#5B3FD6}}
:root[data-theme="light"] .part:nth-child(5){--pc:#5B3FD6}

/* ===== gallery (2026-10-13, J: "a shit ton of beautiful colorful fractals, and not mostly text") ===== */
.wrap.wide{max-width:min(1600px,100%)}
.g-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.g-tile,.g-hl{position:relative;display:block;border-radius:10px;overflow:hidden;border:1px solid var(--line);background:#000;
  aspect-ratio:16/10;text-decoration:none;color:#fff}
.g-tile img,.g-hl img{display:block;width:100%;height:100%;object-fit:cover;transition:transform .5s ease}
.g-tile:hover img,.g-hl:hover img,.g-tile:focus-visible img{transform:scale(1.05)}
.g-tile span,.g-hl span{position:absolute;left:0;right:0;bottom:0;padding:22px 12px 10px;font:600 1rem/1.25 var(--f-body);
  background:linear-gradient(transparent,rgba(0,0,0,.78));text-shadow:0 1px 2px #000}
.g-tile[hidden]{display:none}
/* chapter band: pictures first, right under the title */
.g-band{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:10px;align-items:stretch}
.g-band .g-more{display:grid;place-items:center;border:1px dashed var(--accent);border-radius:10px;color:var(--accent);
  font:700 1.05rem var(--f-display);text-decoration:none;min-height:120px}
/* hub hero: big crossfading renders */
.g-hero{position:relative;aspect-ratio:16/9;border-radius:14px;overflow:hidden;border:1px solid var(--line);background:#000}
.g-hero img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity 1.6s ease}
.g-hero img.on{opacity:1}
.g-hero-cap{position:absolute;left:0;right:0;bottom:0;display:flex;justify-content:space-between;gap:12px;align-items:end;
  padding:40px 18px 14px;background:linear-gradient(transparent,rgba(0,0,0,.75));color:#fff;text-decoration:none}
.g-hero-cap b{font:700 clamp(1.1rem,2.4vw,1.6rem) var(--f-display);text-shadow:0 1px 3px #000}
.g-hero-cap span{font:600 1rem var(--f-body);color:#F2C14E;white-space:nowrap}
.g-hls{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:12px}
.btn-gal{display:inline-block;margin-top:6px;padding:12px 20px;border-radius:10px;border:1px solid var(--accent);
  color:var(--accent);font:700 1.05rem var(--f-display);text-decoration:none}
/* lightbox */
.g-lb{border:0;padding:0;max-width:96vw;max-height:94vh;background:#000;color:#fff;border-radius:12px;overflow:hidden}
.g-lb::backdrop{background:rgba(5,3,12,.88)}
.g-lb img{display:block;max-width:96vw;max-height:80vh;width:auto;height:auto;margin:auto}
.g-lb-cap{display:grid;gap:4px;padding:12px 18px 16px;font:400 1.05rem/1.45 var(--f-body)}
.g-lb-cap b{font:700 1.25rem var(--f-display)}
.g-lb-go{color:#F2C14E;font-weight:600}
.g-lb button{position:absolute;background:rgba(0,0,0,.55);color:#fff;border:1px solid rgba(255,255,255,.3);border-radius:50%;
  width:48px;height:48px;font-size:1.8rem;line-height:1;cursor:pointer}
.g-lb-x{top:10px;right:10px}.g-lb-p{left:10px;top:40%}.g-lb-n{right:10px;top:40%}
@media (prefers-reduced-motion:reduce){.g-hero img{transition:none}.g-tile img,.g-hl img{transition:none}}
@media (max-width:560px){.g-grid{grid-template-columns:1fr 1fr;gap:8px}.g-tile span{font-size:.85rem;padding:16px 8px 6px}}
/* inline pictures sprinkled between chapter sections */
.g-inline{margin:8px 0;display:grid;gap:10px}
.g-inline .g-tile{aspect-ratio:21/9;border-radius:14px}
.g-inline .g-tile span{display:none}
.g-inline figcaption{font:400 1rem/1.5 var(--f-body);color:var(--muted)}
.g-inline figcaption b{color:var(--ink);margin-right:6px}
.g-inline figcaption a{color:var(--accent);white-space:nowrap}

/* long source URLs and DOIs must wrap on phones instead of widening the page grid (found at 390 px, 2026-10-22) */
#sources li,#sources a{overflow-wrap:anywhere}