/* CalcPond — shared stylesheet. System fonts, mobile-first, no external requests. */
:root{
  --bg:#f7f9fb; --surface:#ffffff; --ink:#16202a; --muted:#5b6b7a;
  --line:#e3e9ef; --brand:#0d7d6e; --brand-dark:#0a6053; --brand-tint:#e6f4f1;
  --accent:#f2994a; --danger:#c0392b; --radius:12px; --shadow:0 1px 3px rgba(16,32,42,.06),0 8px 24px rgba(16,32,42,.05);
  --maxw:760px;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  font-size:17px; line-height:1.65; -webkit-font-smoothing:antialiased;
}
a{color:var(--brand-dark); text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%;height:auto}

/* Layout */
.wrap{max-width:var(--maxw); margin:0 auto; padding:0 18px}
main{padding:26px 0 48px}
section{margin:0 0 26px}

/* Header */
.site-head{background:var(--surface); border-bottom:1px solid var(--line); position:sticky; top:0; z-index:50}
.site-head .wrap{display:flex; align-items:center; justify-content:space-between; height:58px}
.brand{display:flex; align-items:center; gap:9px; font-weight:700; font-size:19px; color:var(--ink)}
.brand:hover{text-decoration:none}
.brand .logo{width:26px;height:26px;flex:0 0 26px}
.nav-toggle{background:none;border:0;padding:8px;cursor:pointer;display:none;color:var(--ink)}
.nav a{color:var(--ink); font-size:15px; font-weight:500; padding:6px 2px}
.nav{display:flex; gap:18px; align-items:center}

/* Hero */
.hero{text-align:center; padding:34px 0 10px}
.hero h1{font-size:30px; line-height:1.2; margin:0 0 10px}
.hero p{color:var(--muted); font-size:18px; margin:0 auto; max-width:560px}

/* Tool grid */
.grid{display:grid; grid-template-columns:repeat(2,1fr); gap:14px}
.card{
  display:block; background:var(--surface); border:1px solid var(--line);
  border-radius:var(--radius); padding:18px; box-shadow:var(--shadow); transition:transform .12s ease,border-color .12s ease;
}
.card:hover{transform:translateY(-2px); border-color:var(--brand); text-decoration:none}
.card h3{margin:8px 0 4px; font-size:17px; color:var(--ink)}
.card p{margin:0; color:var(--muted); font-size:14px}
.card .ico{width:30px;height:30px;color:var(--brand)}

/* Tool page */
.tool-card{background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:20px; box-shadow:var(--shadow)}
.field{margin:0 0 15px}
.field label{display:block; font-weight:600; font-size:15px; margin-bottom:6px}
.field .hint{font-weight:400; color:var(--muted); font-size:13px}
input[type=number],input[type=text],input[type=date],select{
  width:100%; padding:12px 13px; font-size:16px; border:1px solid var(--line);
  border-radius:10px; background:#fff; color:var(--ink); font-family:inherit;
}
input:focus,select:focus{outline:2px solid var(--brand-tint); border-color:var(--brand)}
.row{display:flex; gap:10px}
.row>*{flex:1}
.seg{display:flex; border:1px solid var(--line); border-radius:10px; overflow:hidden}
.seg button{flex:1; padding:11px; background:#fff; border:0; font-size:15px; font-weight:600; color:var(--muted); cursor:pointer; font-family:inherit}
.seg button.on{background:var(--brand); color:#fff}
.btn{
  width:100%; padding:14px; font-size:17px; font-weight:700; color:#fff;
  background:var(--brand); border:0; border-radius:10px; cursor:pointer; font-family:inherit;
}
.btn:hover{background:var(--brand-dark)}
.btn.sec{background:#fff;color:var(--brand-dark);border:1px solid var(--line)}
.result{
  margin-top:16px; background:var(--brand-tint); border:1px solid #cfe8e2;
  border-radius:10px; padding:16px; display:none;
}
.result.show{display:block}
.result .big{font-size:28px; font-weight:700; color:var(--brand-dark); line-height:1.25}
.result .sub{color:var(--muted); font-size:14px; margin-top:4px}
.result table{width:100%; border-collapse:collapse; margin-top:10px; font-size:14px}
.result td{padding:5px 0; border-bottom:1px solid #cfe8e2}
.result td:last-child{text-align:right; font-variant-numeric:tabular-nums; font-weight:600}
.err{color:var(--danger); font-size:14px; margin-top:8px; display:none}
.err.show{display:block}

/* Content */
.prose h2{font-size:22px; margin:30px 0 10px}
.prose h3{font-size:18px; margin:22px 0 8px}
.prose p,.prose li{color:#2c3945}
.prose ul,.prose ol{padding-left:22px}
.prose table{width:100%; border-collapse:collapse; margin:14px 0; font-size:15px}
.prose th,.prose td{border:1px solid var(--line); padding:8px 10px; text-align:left}
.prose th{background:var(--brand-tint)}
.callout{background:#fff8ef; border:1px solid #f6e1c4; border-radius:10px; padding:14px 16px; margin:16px 0}
.callout strong{color:var(--accent)}

/* FAQ */
.faq details{background:var(--surface); border:1px solid var(--line); border-radius:10px; padding:0 16px; margin-bottom:10px}
.faq summary{cursor:pointer; padding:14px 0; font-weight:600; list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+"; float:right; color:var(--brand); font-weight:700}
.faq details[open] summary::after{content:"\2013"}
.faq details[open] summary{border-bottom:1px solid var(--line)}
.faq p{padding:12px 0; margin:0; color:#2c3945}

/* Breadcrumb + related */
.crumb{font-size:13px; color:var(--muted); margin:4px 0 14px}
.crumb a{color:var(--muted)}
.related{display:grid; grid-template-columns:repeat(3,1fr); gap:12px; margin-top:12px}
.related a{display:block; background:var(--surface); border:1px solid var(--line); border-radius:10px; padding:12px; font-size:14px; font-weight:600; text-align:center}
.related a:hover{border-color:var(--brand); text-decoration:none}

/* Footer */
.site-foot{background:#12242a; color:#c4d2d6; padding:30px 0; font-size:14px; margin-top:30px}
.site-foot a{color:#a9e3d8}
.foot-links{display:flex; flex-wrap:wrap; gap:14px; margin-bottom:14px}
.site-foot .fine{color:#7f979d; font-size:13px}

@media (max-width:560px){
  body{font-size:16px}
  .hero h1{font-size:25px}
  .nav{position:fixed; inset:58px 0 auto 0; background:var(--surface); flex-direction:column; align-items:stretch; gap:0; border-bottom:1px solid var(--line); box-shadow:var(--shadow); transform:translateY(-140%); transition:transform .2s ease}
  .nav.open{transform:none}
  .nav a{padding:14px 18px; border-bottom:1px solid var(--line)}
  .nav-toggle{display:block}
  .related{grid-template-columns:1fr}
}