/* CalcKit design system — shared by all tool sites
   light, editorial, high-contrast; no external deps */

:root{
  --bg:#ffffff;
  --bg-soft:#f7f8fb;
  --bg-tint:#eef2ff;
  --ink:#101828;
  --ink-2:#475467;
  --ink-3:#667085;
  --line:#e4e7ec;
  --line-2:#d0d5dd;
  --accent:#2f5bea;
  --accent-dark:#1d3fb8;
  --accent-soft:#eaf0ff;
  --ok:#067647;
  --ok-soft:#ecfdf3;
  --warn:#b54708;
  --warn-soft:#fffaeb;
  --bad:#b42318;
  --bad-soft:#fef3f2;
  --radius:14px;
  --radius-sm:10px;
  --shadow-sm:0 1px 2px rgba(16,24,40,.06);
  --shadow:0 4px 16px rgba(16,24,40,.08);
  --shadow-lg:0 18px 48px rgba(16,24,40,.10);
  --sans:-apple-system,BlinkMacSystemFont,"Segoe UI","Inter","Helvetica Neue",Arial,"Noto Sans",sans-serif;
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace;
  --wrap:1100px;
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{
  margin:0;background:var(--bg);color:var(--ink);
  font-family:var(--sans);font-size:16px;line-height:1.65;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
img,svg{max-width:100%;display:block}
[hidden]{display:none !important}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4{margin:0 0 .5em;line-height:1.2;letter-spacing:-.02em;font-weight:700}
h1{font-size:clamp(1.9rem,4vw,2.65rem)}
h2{font-size:clamp(1.35rem,2.4vw,1.65rem);margin-top:2.2em}
h3{font-size:1.12rem;margin-top:1.6em}
p{margin:0 0 1em}
ul,ol{margin:0 0 1.2em;padding-left:1.25em}
li{margin:.35em 0}
code,kbd{font-family:var(--mono);font-size:.9em;background:var(--bg-soft);border:1px solid var(--line);border-radius:6px;padding:.1em .35em}
hr{border:0;border-top:1px solid var(--line);margin:2.5em 0}

.wrap{width:100%;max-width:var(--wrap);margin:0 auto;padding:0 20px}
.skip{position:absolute;left:-9999px}
.skip:focus{left:12px;top:12px;background:#fff;padding:10px 14px;border-radius:8px;z-index:99;box-shadow:var(--shadow)}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:50;background:rgba(255,255,255,.88);
  backdrop-filter:saturate(180%) blur(10px);border-bottom:1px solid var(--line);
}
.header-in{display:flex;align-items:center;justify-content:space-between;gap:16px;height:64px}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;color:var(--ink);letter-spacing:-.02em;font-size:1.02rem}
.brand:hover{text-decoration:none}
.brand .mark{
  width:30px;height:30px;border-radius:9px;background:linear-gradient(140deg,var(--accent),#7c3aed);
  color:#fff;display:grid;place-items:center;font-size:.82rem;font-weight:800;letter-spacing:-.03em;flex:none;
}
.nav{display:flex;align-items:center;gap:22px}
.nav a{color:var(--ink-2);font-size:.94rem;font-weight:500}
.nav a:hover{color:var(--ink);text-decoration:none}
.nav a.active{color:var(--accent)}

/* ---------- hero ---------- */
.hero{padding:46px 0 10px;border-bottom:1px solid var(--line);background:
  radial-gradient(900px 320px at 50% -160px,var(--accent-soft),transparent 70%);}
.hero .eyebrow{
  display:inline-flex;align-items:center;gap:7px;background:var(--accent-soft);color:var(--accent-dark);
  font-size:.78rem;font-weight:600;letter-spacing:.04em;text-transform:uppercase;
  padding:6px 11px;border-radius:999px;margin-bottom:16px;
}
.hero h1{max-width:20ch}
.hero .lede{font-size:1.12rem;color:var(--ink-2);max-width:62ch;margin-bottom:26px}

/* ---------- tool card ---------- */
.tool{
  background:#fff;border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow-lg);margin:0 0 40px;overflow:hidden;
}
.tool-head{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:16px 22px;border-bottom:1px solid var(--line);background:var(--bg-soft);
}
.tool-head .tt{font-weight:600;font-size:.95rem;color:var(--ink)}
.tool-head .hint{font-size:.8rem;color:var(--ink-3)}
.tool-body{padding:24px 22px}
.tabs{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:22px}
.tab{
  border:1px solid var(--line-2);background:#fff;color:var(--ink-2);
  padding:9px 14px;border-radius:999px;font-size:.88rem;font-weight:500;cursor:pointer;
  transition:.15s border-color,.15s background,.15s color;font-family:inherit;
}
.tab:hover{border-color:var(--accent);color:var(--accent)}
.tab[aria-selected="true"]{background:var(--accent);border-color:var(--accent);color:#fff}

.field-grid{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(190px,1fr))}
.field{display:flex;flex-direction:column;gap:7px}
.field label{font-size:.86rem;font-weight:600;color:var(--ink-2)}
.field .sub{font-size:.78rem;color:var(--ink-3);font-weight:400}
input[type=number],input[type=text],input[type=date],select{
  width:100%;padding:12px 14px;border:1px solid var(--line-2);border-radius:var(--radius-sm);
  font-size:1rem;font-family:inherit;color:var(--ink);background:#fff;
  transition:.15s border-color,.15s box-shadow;
}
input:focus,select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(47,91,234,.15)}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  background:var(--accent);color:#fff;border:1px solid var(--accent);
  padding:12px 22px;border-radius:var(--radius-sm);font-size:.98rem;font-weight:600;
  font-family:inherit;cursor:pointer;transition:.15s background,.15s transform;
}
.btn:hover{background:var(--accent-dark);border-color:var(--accent-dark)}
.btn:active{transform:translateY(1px)}
.btn.ghost{background:#fff;color:var(--ink-2);border-color:var(--line-2)}
.btn.ghost:hover{background:var(--bg-soft);color:var(--ink)}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:20px}

.result{
  margin-top:24px;padding:22px;border:1px solid var(--line);border-radius:var(--radius);
  background:linear-gradient(180deg,#fbfcff,#f6f8ff);
}
.result-label{font-size:.8rem;letter-spacing:.05em;text-transform:uppercase;color:var(--ink-3);font-weight:600}
.result-value{
  font-size:clamp(1.9rem,5vw,2.6rem);font-weight:750;letter-spacing:-.03em;line-height:1.1;
  font-variant-numeric:tabular-nums;margin:4px 0 2px;color:var(--ink);
}
.result-sub{color:var(--ink-2);font-size:.95rem}
.result-note{margin-top:10px;font-size:.86rem;color:var(--ink-3)}
.kv{display:grid;grid-template-columns:repeat(auto-fit,minmax(130px,1fr));gap:14px;margin-top:18px}
.kv .cell{background:#fff;border:1px solid var(--line);border-radius:var(--radius-sm);padding:12px 14px}
.kv .k{font-size:.76rem;color:var(--ink-3);text-transform:uppercase;letter-spacing:.04em}
.kv .v{font-size:1.05rem;font-weight:650;font-variant-numeric:tabular-nums}
.pill{display:inline-block;padding:4px 10px;border-radius:999px;font-size:.82rem;font-weight:600}
.pill.ok{background:var(--ok-soft);color:var(--ok)}
.pill.warn{background:var(--warn-soft);color:var(--warn)}
.pill.bad{background:var(--bad-soft);color:var(--bad)}
.pill.neutral{background:var(--bg-soft);color:var(--ink-2);border:1px solid var(--line)}

table{width:100%;border-collapse:collapse;margin:1.2em 0;font-size:.94rem}
th,td{text-align:left;padding:11px 12px;border-bottom:1px solid var(--line)}
th{font-size:.8rem;text-transform:uppercase;letter-spacing:.04em;color:var(--ink-3);font-weight:600;background:var(--bg-soft)}
tbody tr:hover{background:#fcfcfe}
.table-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:var(--radius-sm)}
.table-scroll table{margin:0}
.table-scroll th,.table-scroll td{white-space:nowrap}

.callout{
  border-left:3px solid var(--accent);background:var(--bg-soft);
  padding:14px 18px;border-radius:0 var(--radius-sm) var(--radius-sm) 0;margin:1.4em 0;color:var(--ink-2);
}
.callout strong{color:var(--ink)}

/* ---------- prose ---------- */
.prose{max-width:72ch}
.prose h2{margin-top:2.4em}
.prose h3{margin-top:1.8em}
.prose .formula{
  font-family:var(--mono);font-size:.92rem;background:var(--bg-soft);border:1px solid var(--line);
  border-radius:var(--radius-sm);padding:14px 16px;overflow-x:auto;margin:1.1em 0;color:var(--ink);
}

/* ---------- faq ---------- */
.faq{border-top:1px solid var(--line);margin-top:44px;padding-top:8px}
details{border-bottom:1px solid var(--line);padding:16px 0}
summary{
  cursor:pointer;font-weight:600;color:var(--ink);list-style:none;
  display:flex;align-items:flex-start;justify-content:space-between;gap:16px;
}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";font-size:1.25rem;line-height:1;color:var(--ink-3);flex:none}
details[open] summary::after{content:"–"}
details p{margin:12px 0 0;color:var(--ink-2)}

/* ---------- related ---------- */
.related{margin:52px 0 0}
.cards{display:grid;gap:14px;grid-template-columns:repeat(auto-fit,minmax(230px,1fr))}
.card{
  display:block;padding:18px;border:1px solid var(--line);border-radius:var(--radius);
  background:#fff;box-shadow:var(--shadow-sm);transition:.15s border-color,.15s box-shadow,.15s transform;
}
.card:hover{border-color:var(--accent);box-shadow:var(--shadow);text-decoration:none;transform:translateY(-2px)}
.card .card-title{font-weight:650;color:var(--ink);margin-bottom:4px}
.card .card-desc{font-size:.88rem;color:var(--ink-3);line-height:1.5}

/* ---------- footer ---------- */
.site-footer{margin-top:72px;border-top:1px solid var(--line);background:var(--bg-soft);padding:34px 0 30px}
.footer-in{display:flex;flex-wrap:wrap;gap:24px;justify-content:space-between;align-items:flex-start}
.footer-brand{max-width:34ch;font-size:.9rem;color:var(--ink-3)}
.footer-brand .brand{margin-bottom:8px}
.footer-links{display:flex;flex-wrap:wrap;gap:28px}
.footer-links h4{font-size:.78rem;text-transform:uppercase;letter-spacing:.06em;color:var(--ink-3);margin-bottom:10px}
.footer-links ul{list-style:none;margin:0;padding:0}
.footer-links li{margin:0 0 6px}
.footer-links a{color:var(--ink-2);font-size:.9rem}
.copyright{margin-top:26px;padding-top:18px;border-top:1px solid var(--line);font-size:.82rem;color:var(--ink-3);display:flex;flex-wrap:wrap;gap:10px;justify-content:space-between}

/* ---------- doc pages ---------- */
.doc{padding:44px 0 10px}
.doc h1{margin-bottom:.35em}
.doc .meta{color:var(--ink-3);font-size:.9rem;margin-bottom:2em}

@media (max-width:720px){
  .nav{gap:14px}
  .nav a:not(.active){display:none}
  .hero{padding:32px 0 6px}
  .tool-body{padding:18px 16px}
  .result{padding:18px}
  .footer-in{gap:18px}
}
@media print{
  .site-header,.site-footer,.related,.nav,.actions{display:none}
  .tool{box-shadow:none}
}

/* ---------- trust row ---------- */
.trust{display:flex;flex-wrap:wrap;gap:10px 22px;list-style:none;padding:0;margin:0 0 28px}
.trust li{display:flex;align-items:center;gap:7px;color:var(--ink-3);font-size:.9rem}
.trust li::before{content:"\2713";color:var(--ok);font-weight:700;font-size:.95rem;line-height:1}

/* ---------- mobile hardening ---------- */
@media (max-width:560px){
  .tool-body{padding:16px 14px}
  .field-grid{grid-template-columns:1fr;gap:14px}
  .result{padding:16px}
  .result-value{font-size:1.75rem}
  .hero .lede{font-size:1.03rem}
  .tabs{gap:6px}
  .tab{padding:8px 12px;font-size:.84rem}
  .kv{grid-template-columns:1fr 1fr;gap:10px}
  .actions .btn{flex:1 1 auto}
  .footer-links{gap:20px}
  .table-scroll{-webkit-overflow-scrolling:touch}
}

/* ---------- language switcher ---------- */
.langs{display:flex;align-items:center;gap:4px;margin-left:auto}
.langs a{font-size:.76rem;font-weight:600;letter-spacing:.03em;color:var(--ink-3);padding:5px 7px;
  border-radius:6px;text-decoration:none}
.langs a:hover{background:var(--bg-soft);color:var(--ink)}
.langs a.on{background:var(--accent-soft);color:var(--accent-dark)}
@media (max-width:720px){
  .langs{gap:0}
  .langs a{padding:4px 5px;font-size:.72rem}
}