/* ============================================================================
   SpecCalcs — blueprint / technical-drawing visual system
   Drafting-paper canvas + fine grid + ink header/result blocks + Plex fonts.
   Light-first (fast, ad-friendly, readable); dark mode mirrors it.
   ============================================================================ */
:root{
  --paper:#eef1f4;            /* drafting paper */
  --sheet:#ffffff;            /* content sheet */
  --grid:rgba(20,45,64,.055); /* blueprint grid line */
  --ink:#14212b;             /* pen / dark blocks */
  --ink-soft:#33454f;
  --fg:#16232d;
  --muted:#5d6b75;
  --line:#d3dae0;
  --accent:#0a7d8c;          /* technical cyan-teal */
  --accent-2:#e8590c;        /* safety orange — warnings/highlights */
  --accent-ink:#7fdbe8;      /* accent on dark */
  --result-bg:#14212b;
  --warn-bg:#fff6ec;--warn-line:#f0c48a;
  --max:1040px;--radius:6px;
  --mono:'IBM Plex Mono',ui-monospace,SFMono-Regular,Menlo,monospace;
}
@media (prefers-color-scheme:dark){
  :root{
    --paper:#0e171e;--sheet:#131f28;--grid:rgba(127,219,232,.06);
    --ink:#0a1319;--ink-soft:#1c2b35;--fg:#e4e9ec;--muted:#93a1ab;--line:#263440;
    --accent:#39b3c4;--accent-2:#ff7a3d;--accent-ink:#7fdbe8;--result-bg:#0a1319;
    --warn-bg:#241a0f;--warn-line:#5a4526;
  }
}
*{box-sizing:border-box}
html{
  font:17px/1.7 'DM Sans',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  -webkit-text-size-adjust:100%;
}
body{margin:0;color:var(--fg);background:var(--paper)}
/* Apple-style type scale: big, tight, heavy headings vs. relaxed body */
h1,h2,h3{line-height:1.08;font-weight:700;letter-spacing:-.028em}
h1{font-size:clamp(2.1rem,5vw,3rem);margin:.3em 0 .35em}
h2{font-size:clamp(1.5rem,3vw,2rem);margin:1.7em 0 .5em}
h3{font-size:1.2rem;font-weight:600;letter-spacing:-.02em;margin:1.4em 0 .4em}
p{margin:0 0 1em}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
code,.mono,.num{font-family:var(--mono)}

/* ---- header: ink bar ---- */
.site-head{background:var(--ink);color:#fff;border-bottom:2px solid var(--accent)}
.site-head .wrap{max-width:var(--max);margin:0 auto;padding:12px 20px;
  display:flex;align-items:center;gap:28px;flex-wrap:wrap}
.brand{font-weight:600;font-size:1.15rem;color:#fff;text-decoration:none;
  display:flex;align-items:center;gap:9px;letter-spacing:-.02em}
.brand .mk{font-family:var(--mono);color:var(--accent-ink);font-weight:600}
.mainnav{display:flex;gap:20px;flex-wrap:wrap}
.mainnav a{color:#c6d2da;font-size:.92rem;font-weight:500;text-decoration:none}
.mainnav a:hover{color:#fff}
.lang-pick{margin-left:auto;font-family:var(--mono);font-size:.8rem;color:#8fa0ab}

main{max-width:var(--max);margin:0 auto;padding:0 20px 56px}
.crumbs{font-size:.82rem;color:var(--muted);padding:14px 0 4px;font-family:var(--mono)}
.crumbs ol{list-style:none;display:flex;flex-wrap:wrap;gap:7px;margin:0;padding:0}
.crumbs li:not(:last-child)::after{content:"/";margin-left:7px;opacity:.5}

/* ---- content sheet ---- */
.sheet{background:var(--sheet);border:1px solid var(--line);border-radius:10px;
  padding:32px 38px;margin:16px 0}
.lead{font-size:1.12rem;line-height:1.55;font-weight:400;margin:.1em 0 .7em;color:var(--ink-soft);max-width:66ch}
.lead .num,.lead strong{font-weight:600}
.dims{color:var(--muted);font-size:.9rem;font-family:var(--mono);margin-bottom:1.2em}
/* long-form technical prose */
.prose{max-width:68ch}
.prose p{margin:0 0 1.1em;color:var(--ink-soft)}
.prose h2{margin-top:1.9em}
.prose ul{margin:0 0 1.2em;padding-left:1.3em}
.prose li{margin:.4em 0;color:var(--ink-soft)}
.prose strong{font-weight:600;color:var(--fg)}
.prose .lead-in{font-weight:600;color:var(--fg)}

/* ---- calculator widget ---- */
.widget{border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;margin:20px 0}
.widget-head{background:var(--ink-soft);color:#fff;padding:9px 16px;font-size:.82rem;
  font-family:var(--mono);letter-spacing:.04em;text-transform:uppercase;
  display:flex;align-items:center;gap:8px}
.widget-head::before{content:"";width:8px;height:8px;background:var(--accent-ink);border-radius:1px}
.widget-body{padding:18px 16px;background:var(--sheet)}
.controls{display:flex;flex-wrap:wrap;gap:14px}
.controls label{display:flex;flex-direction:column;font-size:.78rem;color:var(--muted);
  gap:5px;font-family:var(--mono);text-transform:uppercase;letter-spacing:.03em}
.controls select,.controls input{font-size:1rem;font-family:var(--mono);padding:9px 11px;
  border:1px solid var(--line);border-radius:4px;background:var(--paper);color:var(--fg);min-width:160px}
.controls select:focus,.controls input:focus{outline:2px solid var(--accent);border-color:var(--accent)}
.result{display:block;margin-top:16px;background:var(--result-bg);color:#fff;
  border-radius:4px;padding:18px 20px;border-left:3px solid var(--accent-ink)}
.result .big{font-family:var(--mono);font-size:1.85rem;font-weight:600;line-height:1.15;letter-spacing:-.01em}
.result .big span{font-size:.95rem;font-weight:400;opacity:.7}
.result .sub{color:#a9c5cd;font-size:.82rem;margin-top:8px;font-family:var(--mono)}
.result .err{margin:0;color:#ffb3a0}

/* ---- formula block (KaTeX) ---- */
.formula{background:var(--paper);border:1px solid var(--line);border-left:3px solid var(--accent);
  border-radius:4px;padding:14px 18px;margin:16px 0;overflow-x:auto}
.formula .lbl{font-family:var(--mono);font-size:.72rem;text-transform:uppercase;
  letter-spacing:.05em;color:var(--muted);margin-bottom:8px}
.formula .katex{font-size:1.15em}
.formula .where{font-size:.85rem;color:var(--muted);margin-top:10px;line-height:1.5}

/* ---- spec tables ---- */
.table-wrap{overflow-x:auto;margin:12px 0}
table.spec{border-collapse:collapse;width:100%;font-size:.9rem;font-family:var(--mono)}
table.spec th,table.spec td{border:1px solid var(--line);padding:8px 11px;text-align:center;white-space:nowrap}
table.spec thead th{background:var(--ink);color:#fff;font-weight:500;font-size:.82rem}
table.spec thead th small{color:var(--accent-ink);font-weight:400}
table.spec tbody th{text-align:left;background:var(--paper);font-weight:600}
table.spec tbody tr:nth-child(even) td{background:rgba(20,45,64,.02)}
table.kv th{width:46%}

.note{background:var(--warn-bg);border:1px solid var(--warn-line);border-left:3px solid var(--accent-2);
  border-radius:4px;padding:13px 16px;font-size:.92rem;margin:16px 0}
.xlink{font-size:.94rem;font-family:var(--mono)}

/* ---- homepage directory ---- */
.hero{background:var(--ink);color:#fff;border-radius:12px;padding:54px 40px;margin:22px 0 34px;border:1px solid var(--line)}
.hero h1{color:#fff;font-size:clamp(2.4rem,6vw,3.6rem);margin:0 0 .25em;letter-spacing:-.035em}
.hero p{color:#c4d2db;font-size:1.08rem;line-height:1.55;max-width:60ch;margin:0;font-weight:400}
.hero .mk{font-family:var(--mono);color:var(--accent-ink);font-weight:500}

.domain{margin:44px 0}
.domain-head{display:flex;align-items:baseline;gap:14px;flex-wrap:wrap;
  border-bottom:2px solid var(--ink);padding-bottom:10px;margin-bottom:18px}
.domain-head .dno{font-family:var(--mono);font-size:.95rem;font-weight:600;color:var(--accent);
  align-self:center;padding-top:.15em}
.domain-head h2{margin:0;font-size:clamp(1.6rem,3vw,2rem);letter-spacing:-.03em}
.domain-head .blurb{color:var(--muted);font-size:1rem;font-weight:400}
.calc-grid{list-style:none;padding:0;margin:0;display:grid;
  grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
.calc-card{display:flex;flex-direction:column;padding:15px 16px;border:1px solid var(--line);
  border-radius:var(--radius);background:var(--sheet);text-decoration:none;color:var(--fg);
  transition:border-color .12s,transform .12s}
.calc-card:hover{border-color:var(--accent);transform:translateY(-1px);text-decoration:none}
.calc-card .cname{font-weight:600;display:flex;align-items:center;gap:8px}
.calc-card .cname::before{content:"→";font-family:var(--mono);color:var(--accent)}
.calc-card .cdesc{color:var(--muted);font-size:.85rem;margin-top:5px}
.calc-card.soon{opacity:.55;pointer-events:none;background:var(--paper)}
.calc-card.soon .cname::before{content:"·";color:var(--muted)}
.calc-card.soon .tag{font-family:var(--mono);font-size:.68rem;text-transform:uppercase;
  color:var(--muted);margin-top:5px;letter-spacing:.05em}

/* hub grid (size lists) */
.grid{list-style:none;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(108px,1fr));gap:8px}
.grid a{display:block;text-align:center;padding:11px 8px;border:1px solid var(--line);border-radius:4px;
  text-decoration:none;background:var(--sheet);font-family:var(--mono);font-size:.9rem}
.grid a:hover{border-color:var(--accent);text-decoration:none}

/* ---- footer ---- */
.site-foot{background:var(--ink);color:#9fb0ba;margin-top:48px;border-top:2px solid var(--accent)}
.site-foot .wrap{max-width:var(--max);margin:0 auto;padding:24px 20px;font-size:.84rem}
.site-foot a{color:var(--accent-ink)}
.site-foot .disclaimer{margin-top:10px;font-size:.78rem;opacity:.8;max-width:80ch}

@media (max-width:560px){
  .site-head .wrap{gap:14px}.lang-pick{margin-left:0}
  h1{font-size:1.6rem}.hero h1{font-size:1.7rem}.sheet{padding:18px 16px}
}