/* ══ Paving Calculators — "trade-grade instrument" design system ══
   Warm concrete surfaces, charcoal ink, one hi-vis construction-amber
   accent, signage-grade Archivo type, and calculator results rendered as a
   dark monospace readout. Pure static CSS; fonts load with display:swap so
   the system fallback keeps CWV solid. */
:root{
  --bg:#f4f2ec;            /* warm concrete */
  --bg-panel:#ece9e0;      /* recessed sections */
  --surface:#ffffff;
  --ink:#191b1f;           /* near-black, warm */
  --ink-2:#5c5f66;         /* muted body */
  --line:#e0dccf;          /* warm hairline */
  --line-2:#d0ccbd;
  --brand:#e8620e;         /* hi-vis construction amber */
  --brand-2:#c9500a;       /* hover */
  --brand-wash:#fbeee2;    /* tint */
  --readout:#1a1c20;       /* instrument panel */
  --readout-amber:#ffb648; /* gauge figures */
  --money:#1f7a4d;         /* cost / go */
  --radius:14px;
  --shadow:0 1px 2px rgba(25,27,31,.05), 0 8px 24px -12px rgba(25,27,31,.18);
  --font:'Archivo',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;
  --mono:'JetBrains Mono',ui-monospace,'SF Mono',Menlo,Consolas,monospace;
}
*{box-sizing:border-box}
html{font-size:16px;-webkit-text-size-adjust:100%}
body{
  margin:0;font-family:var(--font);color:var(--ink);line-height:1.62;
  background:var(--bg);
  /* faint blueprint grid */
  background-image:linear-gradient(var(--line) 1px,transparent 1px),linear-gradient(90deg,var(--line) 1px,transparent 1px);
  background-size:44px 44px;background-position:-1px -1px;
  font-feature-settings:'ss01','cv01';
  -webkit-font-smoothing:antialiased;
}
a{color:var(--brand);text-decoration:none;transition:color .15s}
a:hover{color:var(--brand-2)}
h1,h2,h3{letter-spacing:-.02em;line-height:1.1;font-weight:800}
h1{font-size:clamp(1.9rem,4.5vw,2.9rem);margin:.2rem 0 .5rem}
h2{font-size:1.45rem;font-weight:700;margin:2.4rem 0 .7rem;padding-top:.2rem}
h3{font-size:1.06rem;font-weight:700;margin:1.4rem 0 .35rem}
p{margin:.5rem 0 1rem}
.muted{color:var(--ink-2)}
.wrap{max-width:760px;margin:0 auto;padding:1.25rem 1.4rem}
.wrap.wide{max-width:1120px}

/* ── Header ── */
header.site{
  border-bottom:1px solid var(--line);background:rgba(244,242,236,.82);
  backdrop-filter:saturate(140%) blur(8px);position:sticky;top:0;z-index:20;
}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;gap:1rem;padding-top:.85rem;padding-bottom:.85rem}
header.site .brand{display:inline-flex;align-items:center;gap:.6rem;font-weight:800;font-size:1.08rem;color:var(--ink);letter-spacing:-.02em}
header.site .brand::before{
  content:"";width:26px;height:26px;border-radius:7px;
  background:var(--brand);
  background-image:repeating-linear-gradient(-45deg,rgba(0,0,0,.16) 0 3px,transparent 3px 6px);
  box-shadow:inset 0 0 0 1.5px rgba(0,0,0,.12);
}
header.site nav a{color:var(--ink-2);margin-left:1.4rem;font-size:.82rem;font-weight:600;text-transform:uppercase;letter-spacing:.04em}
header.site nav a:hover{color:var(--ink)}

/* ── Page hero ── */
.page-head{padding:2rem 0 .5rem}
.eyebrow{
  display:inline-block;font-size:.72rem;font-weight:700;text-transform:uppercase;
  letter-spacing:.12em;color:var(--brand);background:var(--brand-wash);
  border:1px solid #f3d5bf;padding:.28rem .6rem;border-radius:6px;margin-bottom:.9rem;
}
.page-head .lead{font-size:1.08rem;color:var(--ink-2);max-width:60ch;margin:.4rem 0 0}
.crumb{font-size:.82rem;color:var(--ink-2);margin-bottom:.6rem}
.crumb a{color:var(--ink-2)}.crumb a:hover{color:var(--brand)}

/* ── The tool ── */
.tool{
  background:var(--surface);border:1px solid var(--line-2);border-radius:var(--radius);
  box-shadow:var(--shadow);margin:1.4rem 0;overflow:hidden;
}
.tool form{padding:1.4rem 1.4rem 1.5rem;border-bottom:1px dashed var(--line-2)}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:1rem}
.field label{display:block;font-size:.76rem;font-weight:600;color:var(--ink-2);margin-bottom:.35rem;text-transform:uppercase;letter-spacing:.03em}
.field .unit{font-weight:500;color:var(--brand);text-transform:none;letter-spacing:0}
.field input,.field select{
  width:100%;padding:.7rem .8rem;border:1.5px solid var(--line-2);border-radius:10px;
  font:600 1.05rem var(--font);background:#fcfbf8;color:var(--ink);transition:border-color .15s,box-shadow .15s;
}
.field input:focus,.field select:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(232,98,14,.16);background:#fff}

/* ── Instrument readout (results) ── */
.results{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:1px;
  background:var(--line-2);padding:1px;
}
.result{background:var(--surface);padding:1.05rem 1.2rem;display:flex;flex-direction:column;justify-content:center}
.result .label{font-size:.72rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em;color:var(--ink-2)}
.result .value{font:800 1.55rem/1.1 var(--mono);margin-top:.35rem;letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.result.em{background:var(--readout);background-image:repeating-linear-gradient(90deg,rgba(255,255,255,.03) 0 1px,transparent 1px 40px)}
.result.em .label{color:#9aa0a8}
.result.em .value{color:var(--readout-amber);text-shadow:0 0 18px rgba(255,182,72,.35)}

/* ── Content ── */
.formula-note,.tool + .ad + h2{scroll-margin-top:80px}
table{border-collapse:separate;border-spacing:0;width:100%;margin:.8rem 0;font-size:.95rem;background:var(--surface);border:1px solid var(--line-2);border-radius:12px;overflow:hidden}
th,td{padding:.7rem .9rem;text-align:left;border-bottom:1px solid var(--line)}
th{background:var(--bg-panel);font-size:.78rem;text-transform:uppercase;letter-spacing:.04em;color:var(--ink-2)}
tr:last-child td{border-bottom:none}
td strong{color:var(--ink)}

.faq{border-left:3px solid var(--brand);background:var(--surface);border-radius:0 10px 10px 0;padding:.9rem 1.1rem;margin:.7rem 0;box-shadow:var(--shadow)}
.faq h3{margin:.1rem 0 .3rem}
.faq p{margin:0;color:var(--ink-2)}

.related{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:.7rem;margin:.7rem 0}
.related a{
  display:flex;align-items:center;justify-content:space-between;gap:.5rem;
  border:1px solid var(--line-2);border-radius:12px;padding:.85rem 1rem;background:var(--surface);
  font-weight:600;color:var(--ink);box-shadow:var(--shadow);transition:transform .15s,border-color .15s,color .15s;
}
.related a::after{content:"→";color:var(--brand);transition:transform .15s}
.related a:hover{transform:translateY(-2px);border-color:var(--brand);color:var(--brand)}
.related a:hover::after{transform:translateX(3px)}

.variants{display:flex;flex-wrap:wrap;gap:.5rem;margin:.6rem 0 .2rem}
.variants a{
  font-size:.85rem;font-weight:600;border:1px solid var(--line-2);border-radius:999px;
  padding:.4rem .85rem;background:var(--surface);color:var(--ink);transition:all .15s;
}
.variants a:hover{background:var(--brand);border-color:var(--brand);color:#fff}

/* ── Footer ── */
footer.site{
  margin-top:3.5rem;background:var(--readout);color:#b7bcc4;font-size:.87rem;
  background-image:repeating-linear-gradient(-45deg,rgba(255,255,255,.02) 0 6px,transparent 6px 12px);
}
footer.site .wrap{padding-top:2rem;padding-bottom:2.4rem}
footer.site p{margin:.35rem 0}
footer.site a{color:#dfe3e8;font-weight:500}
footer.site a:hover{color:var(--brand)}

/* ── Ad slots — generous spacing, never adjacent to controls (SOP §6.2) ── */
.ad{margin:2rem 0;min-height:100px;display:flex;align-items:center;justify-content:center}
.ad[aria-hidden]{border:1px dashed var(--line-2);border-radius:12px;color:#b4ad9c;font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;background:rgba(255,255,255,.4)}

/* ── Load-in ── */
main .wrap > *{animation:rise .5s cubic-bezier(.2,.7,.2,1) both}
@keyframes rise{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
@media(prefers-reduced-motion:reduce){main .wrap > *{animation:none}}

@media(max-width:640px){
  .wrap{padding:1rem}
  body{background-size:36px 36px}
  header.site nav a{margin-left:1rem;font-size:.78rem}
  .page-head{padding:1.4rem 0 .3rem}
}