/* Layout: one reading column; calculator pages pair the input form with a sticky result panel, guide text below. Tape-measure ticks mark the header edge. */
:root{
  --bg:#eceef0; --surface:#ffffff; --ink:#1a1e23; --muted:#596270; --line:#d3d8dd;
  --accent:#1f4fbf; --accent-ink:#ffffff; --pencil:#f0bd2a; --pencil-soft:#fbefc6;
  --display:"Barlow Condensed","Arial Narrow",system-ui,sans-serif;
  --body:"Public Sans",system-ui,-apple-system,"Segoe UI",sans-serif;
  --mono:"IBM Plex Mono",ui-monospace,"SFMono-Regular",Menlo,monospace;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#121519; --surface:#1a1f26; --ink:#e7eaee; --muted:#9aa4b0; --line:#2c343e;
  --accent:#86a6ff; --accent-ink:#0f1420; --pencil:#f0bd2a; --pencil-soft:#3a3218; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#121519; --surface:#1a1f26; --ink:#e7eaee; --muted:#9aa4b0; --line:#2c343e;
  --accent:#86a6ff; --accent-ink:#0f1420; --pencil:#f0bd2a; --pencil-soft:#3a3218; color-scheme:dark}

*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--body);font-size:17px;line-height:1.6}
a{color:var(--accent)}
a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid var(--pencil);outline-offset:2px}
.wrap{max-width:1080px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}

/* header */
.top{background:var(--surface);position:relative}
.top::after{content:"";position:absolute;left:0;right:0;bottom:0;height:10px;
  background:
   repeating-linear-gradient(90deg,var(--ink) 0 1px,transparent 1px 48px),
   repeating-linear-gradient(90deg,var(--muted) 0 1px,transparent 1px 12px);
  background-size:100% 10px,100% 5px;background-repeat:no-repeat;background-position:bottom,bottom;opacity:.55}
.top .wrap{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;padding-block:16px 22px}
.brand{font-family:var(--display);font-weight:700;font-size:28px;letter-spacing:.01em;color:var(--ink);text-decoration:none;line-height:1}
.brand span{background:linear-gradient(transparent 62%,var(--pencil) 62%);padding:0 2px}
.units{display:inline-flex;border:1px solid var(--line);border-radius:999px;padding:3px;background:var(--bg)}
.units button{font:600 13px/1 var(--body);letter-spacing:.04em;text-transform:uppercase;border:0;background:transparent;color:var(--muted);padding:8px 14px;border-radius:999px;cursor:pointer}
.units button[aria-pressed="true"]{background:var(--ink);color:var(--surface)}

/* page */
main{padding-block:32px 56px}
.crumbs{font-size:14px;color:var(--muted);margin:0 0 8px}
.crumbs a{color:var(--muted)}
h1,h2,h3{font-family:var(--display);line-height:1.1;text-wrap:balance;margin:0}
h1{font-size:clamp(38px,6vw,58px);font-weight:700}
h2{font-size:30px;font-weight:600;margin-top:40px}
h3{font-size:22px;font-weight:600;margin-top:24px}
.lede{font-size:19px;color:var(--muted);max-width:62ch;margin:12px 0 0}

/* calculator */
.calc{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,1fr);gap:24px;margin-top:28px;align-items:start}
@media (max-width:760px){.calc{grid-template-columns:1fr}}
.form{background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:22px;display:grid;grid-template-columns:1fr 1fr;gap:16px 18px}
@media (max-width:460px){.form{grid-template-columns:1fr}}
.field{display:flex;flex-direction:column;gap:6px;min-width:0}
.field.full{grid-column:1/-1}
.field label{font-size:13px;font-weight:600;letter-spacing:.05em;text-transform:uppercase;color:var(--muted)}
.inp{display:flex;align-items:stretch;border:1px solid var(--line);border-radius:4px;background:var(--bg);overflow:hidden}
.inp:focus-within{border-color:var(--accent)}
.inp input,.inp select{flex:1;min-width:0;border:0;background:transparent;color:var(--ink);font:500 18px var(--mono);padding:10px 12px}
.inp select{font-family:var(--body);font-size:16px}
.inp .u{display:flex;align-items:center;padding:0 12px;font:500 14px var(--mono);color:var(--muted);border-left:1px solid var(--line)}
.result{background:var(--ink);color:var(--surface);border-radius:6px;padding:22px;position:sticky;top:16px}
.result .k{font-size:13px;letter-spacing:.06em;text-transform:uppercase;opacity:.75}
.result .main{font:600 clamp(34px,5vw,46px)/1.1 var(--mono);font-variant-numeric:tabular-nums;margin:6px 0 4px}
.result .main mark{background:none;color:var(--pencil)}
.result dl{margin:18px 0 0;display:grid;gap:10px}
.result dl div{display:flex;justify-content:space-between;gap:12px;border-top:1px solid color-mix(in srgb,var(--surface) 18%,transparent);padding-top:10px}
.result dt{opacity:.8}
.result dd{margin:0;font-family:var(--mono);font-variant-numeric:tabular-nums;text-align:right}
.result .note{font-size:13px;opacity:.7;margin:16px 0 0}

/* guide */
.guide{max-width:68ch}
.guide p,.guide li{color:var(--ink)}
.formula{font-family:var(--mono);background:var(--pencil-soft);border-left:4px solid var(--pencil);padding:12px 14px;border-radius:0 4px 4px 0;overflow-x:auto}
.tbl{overflow-x:auto}
table{border-collapse:collapse;width:100%;font-size:16px}
th,td{text-align:left;padding:8px 10px;border-bottom:1px solid var(--line)}
th{font-size:13px;letter-spacing:.05em;text-transform:uppercase;color:var(--muted)}
td{font-variant-numeric:tabular-nums}
details{border-bottom:1px solid var(--line);padding:12px 0}
summary{cursor:pointer;font-weight:600}
details p{margin:8px 0 0}

/* home + lists */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px;margin-top:24px}
.tool{display:flex;flex-direction:column;gap:6px;background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:18px;text-decoration:none;color:var(--ink)}
.tool:hover{border-color:var(--accent)}
.tool strong{font-family:var(--display);font-size:24px;font-weight:600;line-height:1.1}
.tool span{color:var(--muted);font-size:15px}
.tool em{font-style:normal;font:500 13px var(--mono);color:var(--accent)}
.hero{padding-block:16px 8px}
.hero h1{font-size:clamp(42px,7vw,72px);max-width:16ch}

footer{border-top:1px solid var(--line);padding-block:28px;font-size:14px;color:var(--muted)}
footer .wrap{display:flex;flex-wrap:wrap;gap:12px 24px;justify-content:space-between}
footer nav{display:flex;flex-wrap:wrap;gap:8px 18px}
footer a{color:var(--muted)}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}

/* v2 additions */
.eyebrow{font:600 13px/1.2 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin:0 0 12px}
.search{margin-top:24px;max-width:520px;display:flex;flex-direction:column;gap:6px}
.search label{font-size:13px;font-weight:600;letter-spacing:.05em;text-transform:uppercase;color:var(--muted)}
.search input{font:500 18px var(--body);padding:14px 16px;border:2px solid var(--ink);border-radius:4px;background:var(--surface);color:var(--ink);width:100%}
.copy{margin-top:18px;font:600 14px var(--body);background:transparent;color:var(--surface);border:1px solid color-mix(in srgb,var(--surface) 45%,transparent);border-radius:4px;padding:9px 14px;cursor:pointer}
.copy:hover{border-color:var(--pencil);color:var(--pencil)}
footer .wrap{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr);gap:28px}
@media (max-width:700px){footer .wrap{grid-template-columns:1fr}}
.fcol{display:flex;flex-direction:column;gap:10px;min-width:0}
.fcol strong{font-family:var(--display);font-size:20px;color:var(--ink)}
.fcol nav{display:flex;flex-wrap:wrap;gap:8px 18px}