/* Product Design (9DT0) revision site.
   Structure and type come from StarDash (stardash.live): flat hairline panels,
   uppercase letterspaced micro-labels, a near-black accent for controls. The
   page itself is the pure white of joshcbruce.com.

   COLOUR IS THE PEN, NOT THE PAGE ("marked up", chosen 2026-10-13). Everything
   is black ink on white. Four colours exist and each has one job:
     --hl    highlighter   what the mark scheme rewards (behind text, never text)
     --pen   red pen       the moderator/examiner: marks, margin notes, warnings
     --tick  green         done / correct / top band
     --biro  blue          links and anything that is the student's own
   Sections are told apart by number, never by hue. No purple anywhere. */
@import url("fonts.css");

:root{
  --bg:#ffffff; --panel:#ffffff; --panel2:#f6f6f6; --line:#e4e4e4;
  --line2:#cfcfcf; --text:#111111; --muted:#444444; --dim:#6b6b6b;
  --edge:#dcdcdc; --edge2:#c4c4c4;
  --press:rgba(0,0,0,.14); --onaccent:#fff; --accent:var(--text);
  /* --pen 4.55:1, --tick 5.2:1, --biro 7.6:1 on white; --hl is a fill only */
  --hl:#fff066; --pen:#e5261f; --tick:#0a7d35; --biro:#1b45d1;
  --mono:"D-DIN",ui-monospace,SFMono-Regular,Menlo,monospace;
  --sans:"D-DIN",system-ui,-apple-system,sans-serif;
  --head:"D-DIN Bold","D-DIN",system-ui,sans-serif;
  --r:9px; --r-sm:6px; --r-lg:13px;
}

/* the four pens */
mark{color:inherit;padding:1px 5px;-webkit-box-decoration-break:clone;box-decoration-break:clone;
  background:linear-gradient(104deg,transparent 0,var(--hl) 4px,var(--hl) calc(100% - 4px),transparent 100%)}
.pen{color:var(--pen)}
.note{display:block;color:var(--pen);font-style:italic;padding-left:14px;border-left:2px solid var(--pen)}
.circ{display:inline-block;color:var(--pen);border:1.5px solid var(--pen);border-radius:50%;
  padding:7px 11px;transform:rotate(-4deg);font-family:var(--mono);font-size:11px;
  letter-spacing:.1em;text-transform:uppercase;white-space:nowrap}

*{box-sizing:border-box}
[hidden]{display:none!important}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--sans);
  font-size:17px;line-height:1.55;font-variant-numeric:tabular-nums;
  -webkit-font-smoothing:antialiased}
a{color:inherit}
h1,h2,h3{font-family:var(--head);font-weight:normal;margin:0;line-height:1.1}
h1{font-size:clamp(34px,5.2vw,56px);letter-spacing:-.005em}
h2{font-size:26px}
p{margin:0 0 .9em}
:focus-visible{outline:2px solid var(--biro);outline-offset:2px}

/* ---- header ---- */
.top{display:flex;align-items:center;gap:16px;padding:14px 16px;flex-wrap:wrap}
.mark{font-family:var(--head);font-size:13px;letter-spacing:.16em;text-transform:uppercase;
  text-decoration:none;display:flex;align-items:baseline;gap:8px}
.mark span{font-family:var(--mono);font-size:10.5px;color:var(--dim);letter-spacing:.12em}
.tabs{display:flex;margin-left:auto;border:1px solid var(--edge);border-radius:var(--r);
  overflow:hidden;background:var(--panel)}
.tabs a{font-family:var(--head);letter-spacing:.14em;text-transform:uppercase;font-size:11px;
  color:var(--dim);padding:8px 14px;text-decoration:none;
  transition:color .15s,background .15s,transform .09s ease-out}
.tabs a:hover{color:var(--text)}
.tabs a.on{color:var(--onaccent);background:var(--accent)}
.tabs a:active{transform:scale(.96)}

.wrap{max-width:1120px;margin:0 auto;padding:0 16px 56px}
.hero{padding:44px 0 30px}
.hero p{color:var(--muted);max-width:62ch;margin:14px 0 0}

/* ---- micro-label, the workhorse of the language ---- */
.k{font-family:var(--mono);font-size:10.5px;letter-spacing:.14em;text-transform:uppercase;
  color:var(--dim);display:block}

/* ---- panels ---- */
.card{border:1px solid var(--edge);border-radius:var(--r-lg);background:var(--panel);padding:18px 20px}
a.card{display:block;text-decoration:none;transition:border-color .15s,transform .09s ease-out}
a.card:hover{border-color:var(--edge2)}
a.card:active{transform:scale(.99);background:var(--panel2)}
.grid{display:grid;gap:12px}
.g2{grid-template-columns:repeat(2,minmax(0,1fr))}
.g3{grid-template-columns:repeat(3,minmax(0,1fr))}
.g4{grid-template-columns:repeat(4,minmax(0,1fr))}
.sec{margin-top:34px}
.sec>.k{margin-bottom:10px}

.big{font-family:var(--head);font-size:clamp(26px,3vw,34px);line-height:1;margin-top:8px}
.big small{font-family:var(--mono);font-size:11px;color:var(--dim);margin-left:6px;letter-spacing:.06em}
.half h2{margin:8px 0 8px}
.half p{color:var(--muted);font-size:15.5px}
.half .go{font-family:var(--head);font-size:11px;letter-spacing:.14em;text-transform:uppercase;
  color:var(--biro);margin-top:14px;display:block}

/* ---- buttons ---- */
.btn{font-family:var(--head);font-size:11px;letter-spacing:.14em;text-transform:uppercase;
  display:inline-block;text-decoration:none;cursor:pointer;border:1px solid var(--edge2);
  border-radius:var(--r-sm);background:var(--panel);color:var(--text);padding:10px 16px;
  transition:background .15s,transform .09s ease-out}
.btn.primary{background:var(--accent);color:var(--onaccent);border-color:var(--accent)}
.btn:active{transform:scale(.96)}

/* ---- marks: the stacked bar and its chips ---- */
.marksbar{display:flex;gap:14px;margin:6px 0 2px}
.marksbar>div{min-width:0}
.marksbar .segs{display:flex;gap:2px;height:14px}
.marksbar .segs i{display:block;background:var(--text);border-radius:2px;min-width:3px}
.marksbar .k{margin-top:7px}
.pill{font-family:var(--mono);font-size:10.5px;letter-spacing:.08em;text-transform:uppercase;
  border:1px solid var(--edge2);border-radius:99px;padding:2px 8px;color:var(--muted);white-space:nowrap}

/* ---- progress ---- */
.bar{display:block;height:3px;background:var(--line);border-radius:2px;overflow:hidden;margin-top:10px;max-width:260px}
.bar i{display:block;height:100%;width:0;background:var(--tick);transition:width .3s}

/* ---- NEA hub rows ---- */
.part{margin-top:30px}
.parthead{display:flex;align-items:baseline;gap:12px;border-bottom:1px solid var(--line);
  padding-bottom:8px;margin-bottom:10px}
.parthead h2{font-size:22px}
.parthead .k{white-space:nowrap}
.parthead .circ{margin-left:auto}
/* a.card sets display:block, so the grid needs the same specificity to win */
a.card.row{display:grid;grid-template-columns:44px 1fr auto;gap:14px;align-items:center;
  padding:14px 18px}
.row .t{display:block}
.row .n{font-family:var(--head);font-size:26px;line-height:1}
.row .t{font-family:var(--head);font-size:17px;line-height:1.25}
.row .s{font-size:14px;color:var(--muted);margin-top:2px}
.rows{display:grid;gap:8px}

.foot{margin-top:56px;padding-top:14px;border-top:1px solid var(--line);
  font-family:var(--mono);font-size:10.5px;letter-spacing:.06em;color:var(--dim);line-height:1.7}

/* ---- page with side contents (topic notes, NEA grids) ---- */
.tlayout{display:grid;grid-template-columns:250px minmax(0,1fr);gap:44px;max-width:1340px;margin:0 auto;padding:0 16px 56px 10px}
.toc{position:sticky;top:0;align-self:start;max-height:100vh;overflow:auto;padding:22px 0 30px;font-size:14px;line-height:1.35;
  scrollbar-width:none}
.toc::-webkit-scrollbar{display:none}
.tocbtn{display:none}
.toc .tt{display:block;text-decoration:none;font-family:var(--head);font-size:17px;line-height:1.2;margin-bottom:14px;padding:0 8px}
.toc .tt .k{margin-bottom:4px}
.toc ol{list-style:none;margin:0;padding:0}
.toc .l1{display:block;text-decoration:none;padding:6px 8px;border-radius:var(--r-sm);font-family:var(--head)}
.toc .l1 b{font-weight:normal;font-family:var(--mono);color:var(--dim);margin-right:4px}
.toc ol ol{margin:0 0 6px 18px;border-left:1px solid var(--line)}
.toc .l2{display:block;text-decoration:none;color:var(--muted);padding:3px 10px;font-size:13.5px}
.toc .l2.ex{color:var(--pen)}
.toc a:hover{background:var(--panel2)}
.toc a.on{color:var(--text);background:var(--panel2)}
.toc .l2.on{box-shadow:inset 2px 0 0 var(--text)}
.tocfoot{display:flex;justify-content:space-between;gap:8px;margin-top:18px;padding:12px 8px 0;border-top:1px solid var(--line);font-size:12.5px}
.tocfoot a{text-decoration:none;color:var(--biro)}
.tocfoot a:hover{background:none;text-decoration:underline}
@media(max-width:960px){
  .tlayout{display:block;padding-left:16px}
  .toc{position:sticky;top:0;z-index:20;background:var(--bg);max-height:none;padding:8px 0;border-bottom:1px solid var(--line);overflow:visible}
  .tocbtn{display:inline-block;font-family:var(--head);font-size:11px;letter-spacing:.14em;text-transform:uppercase;
    border:1px solid var(--edge2);border-radius:var(--r-sm);background:var(--panel);padding:9px 14px;cursor:pointer}
  .toclist{display:none;position:absolute;left:0;right:0;top:100%;background:var(--bg);border-bottom:1px solid var(--text);
    max-height:75vh;overflow:auto;padding:12px 4px 16px}
  .toc.open .toclist{display:block}
}
@media print{.toc,.top{display:none}.tlayout{display:block}}

@media(max-width:760px){
  .g2,.g3,.g4{grid-template-columns:1fr}
  .tabs{margin-left:0;width:100%} .tabs a{flex:1;text-align:center;padding:9px 6px}
  .hero{padding:26px 0 20px}
  a.card.row{grid-template-columns:32px 1fr} .row .pill{grid-column:2;justify-self:start}
}
@media(prefers-reduced-motion:reduce){*{transition:none!important}}