:root {
  --ink: #16181c;
  --ink-soft: #4d545e;
  --ink-faint: #8a919c;
  --bg: #f6f6f2;
  --card: #ffffff;
  --line: #e2e1d9;
  --line-dark: #c9c8bd;
  --sun: #b45309;
  --sun-deep: #8a3e06;
  --sun-soft: #faf0e0;
  --volt: #14532d;
  --volt-soft: #e9f2ec;
}
* { box-sizing: border-box; margin: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
  font-family: 'Inter', -apple-system, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.7;
  font-size: 16.5px;
}
header {
  background: var(--card);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
}
.wrap { max-width: 860px; margin: 0 auto; padding: 0 24px; }
header .wrap { display: flex; justify-content: space-between; align-items: center; height: 62px; }
.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 0.02em;
  text-decoration: none;
  color: var(--ink);
}
.brand svg { display: block; }
.brand span { color: var(--sun); }
nav { display: flex; align-items: center; }
nav a {
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-soft);
  text-decoration: none;
  margin-left: 22px;
}
nav a:hover { color: var(--ink); }
main { padding: 52px 0 72px; }
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 11.5px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--sun-deep);
  background: var(--sun-soft);
  border: 1px solid #eeddc2;
  padding: 4px 12px;
  border-radius: 100px;
  margin-bottom: 18px;
}
h1 {
  font-size: clamp(30px, 5.4vw, 44px);
  line-height: 1.12;
  font-weight: 800;
  letter-spacing: -0.025em;
  margin-bottom: 16px;
  max-width: 22ch;
}
.lede {
  color: var(--ink-soft);
  font-size: 18.5px;
  line-height: 1.65;
  margin-bottom: 36px;
  max-width: 58ch;
}
.calc {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: 0 1px 2px rgba(20,20,15,0.04), 0 8px 24px rgba(20,20,15,0.05);
  padding: 30px;
  margin-bottom: 48px;
}
.calc-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 11.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-faint);
  border-bottom: 1px solid var(--line);
  padding-bottom: 14px;
  margin-bottom: 22px;
}
.calc-head::before { content: ''; width: 8px; height: 8px; border-radius: 2px; background: var(--sun); }
.field { margin-bottom: 20px; }
.field label {
  display: block;
  font-size: 14.5px;
  font-weight: 600;
  margin-bottom: 4px;
}
.field .hint { display: block; font-size: 13px; color: var(--ink-faint); font-weight: 400; margin-bottom: 7px; }
.field .row { display: flex; gap: 10px; }
input[type=number], select {
  width: 100%;
  padding: 11px 13px;
  font-size: 16.5px;
  font-family: inherit;
  border: 1px solid var(--line-dark);
  background: #fcfcfa;
  color: var(--ink);
  border-radius: 8px;
  transition: border-color .12s, box-shadow .12s;
}
input[type=number]:hover, select:hover { border-color: var(--ink-faint); }
input[type=number]:focus, select:focus {
  outline: none;
  border-color: var(--sun);
  box-shadow: 0 0 0 3px rgba(180,83,9,0.14);
}
select.unit { max-width: 150px; }
.result {
  background: #fafaf6;
  border: 1px solid var(--line);
  border-radius: 10px;
  margin-top: 26px;
  padding: 20px 22px;
}
.result-label {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 2px;
}
.result-value {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: clamp(34px, 6vw, 44px);
  font-weight: 700;
  color: var(--volt);
  line-height: 1.2;
  letter-spacing: -0.02em;
}
.result-value small { font-size: 17px; font-weight: 500; color: var(--ink-faint); letter-spacing: 0; }
.result-note { font-size: 14.5px; color: var(--ink-soft); margin-top: 8px; max-width: 60ch; }
.badge {
  display: inline-block;
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 12.5px;
  font-weight: 500;
  background: var(--volt-soft);
  color: var(--volt);
  padding: 4px 11px;
  margin: 12px 8px 0 0;
  border-radius: 6px;
}
.badge.warn { background: var(--sun-soft); color: var(--sun-deep); }
article h2 {
  font-size: 23px;
  font-weight: 700;
  letter-spacing: -0.015em;
  margin: 44px 0 14px;
}
article h2::after {
  content: '';
  display: block;
  width: 44px;
  height: 3px;
  background: var(--sun);
  border-radius: 2px;
  margin-top: 8px;
}
article p { margin-bottom: 15px; max-width: 70ch; }
article ul { margin: 0 0 15px 22px; max-width: 68ch; }
article li { margin-bottom: 8px; }
.formula {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  background: var(--ink);
  color: #e8e6df;
  border-radius: 8px;
  padding: 14px 18px;
  margin: 18px 0;
  font-size: 14px;
  line-height: 1.7;
  overflow-x: auto;
  white-space: pre;
}
details {
  border: 1px solid var(--line);
  background: var(--card);
  margin-bottom: 10px;
  border-radius: 8px;
  overflow: hidden;
}
details[open] { border-color: var(--line-dark); }
summary {
  cursor: pointer;
  padding: 14px 18px;
  font-weight: 600;
  font-size: 15.5px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: '+';
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 18px;
  color: var(--ink-faint);
  flex-shrink: 0;
}
details[open] summary::after { content: '\2212'; }
details p { padding: 0 18px 16px; color: var(--ink-soft); }
.related { margin-top: 52px; }
.related h2 { font-size: 20px; }
.cat {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 34px 0 0;
}
.toolgrid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 14px 0 6px; }
.toolcard {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 20px;
  text-decoration: none;
  color: var(--ink);
  transition: border-color .12s, transform .12s, box-shadow .12s;
}
.toolcard:hover {
  border-color: var(--sun);
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(20,20,15,0.07);
}
.toolcard .num {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 12px;
  font-weight: 700;
  color: var(--sun);
  display: block;
  margin-bottom: 6px;
}
.toolcard b { display: block; font-size: 16.5px; margin-bottom: 5px; letter-spacing: -0.01em; }
.toolcard span { font-size: 14px; color: var(--ink-soft); line-height: 1.55; }
.toolcard.soon { border-style: dashed; }
.toolcard.soon b, .toolcard.soon span { color: var(--ink-faint); }
.toolcard.soon .num { color: var(--ink-faint); }
footer {
  border-top: 1px solid var(--line);
  background: var(--card);
  margin-top: 20px;
}
footer .wrap {
  padding-top: 30px;
  padding-bottom: 30px;
  display: flex;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  font-size: 13.5px;
  color: var(--ink-soft);
}
footer .cols { display: flex; gap: 44px; flex-wrap: wrap; }
footer b { display: block; font-size: 11.5px; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: 8px; font-family: 'JetBrains Mono', 'Courier New', monospace; }
footer a { display: block; color: var(--ink-soft); text-decoration: none; margin-bottom: 6px; }
footer a:hover { color: var(--ink); }
footer .fine { max-width: 36ch; font-size: 12.5px; color: var(--ink-faint); line-height: 1.6; }
@media (max-width: 600px) {
  main { padding-top: 36px; }
  .calc { padding: 22px 18px; }
  .toolgrid { grid-template-columns: 1fr; }
  footer .wrap { flex-direction: column; }
}

.diagram {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px 18px 14px;
  margin: 0 0 44px;
}
.diagram svg { width: 100%; height: auto; display: block; }
.diagram figcaption {
  font-size: 13px;
  color: var(--ink-faint);
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--line);
}
.hero-visual { margin: 8px 0 40px; }
.hero-visual svg { width: 100%; height: auto; display: block; }
.result { animation: none; }
.result.pulse { animation: resultPulse .45s ease; }
@keyframes resultPulse {
  0% { box-shadow: 0 0 0 0 rgba(20,83,45,0.25); }
  100% { box-shadow: 0 0 0 12px rgba(20,83,45,0); }
}
.result-value span { transition: opacity .15s; }

body { background-image: radial-gradient(rgba(22,24,28,0.045) 1px, transparent 1px); background-size: 26px 26px; }
header { box-shadow: 0 1px 0 rgba(20,20,15,0.03); }
nav a.cta {
  background: var(--ink);
  color: #fff;
  padding: 8px 15px;
  border-radius: 8px;
  font-weight: 600;
}
nav a.cta:hover { background: var(--sun-deep); color: #fff; }
.trust {
  display: flex;
  gap: 26px;
  flex-wrap: wrap;
  margin: -10px 0 40px;
}
.trust div {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--ink-soft);
}
.trust svg { flex-shrink: 0; }
.crumb {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  font-size: 12px;
  color: var(--ink-faint);
  margin-bottom: 14px;
}
.crumb a { color: var(--ink-faint); text-decoration: none; }
.crumb a:hover { color: var(--sun-deep); }
.crumb b { color: var(--ink-soft); font-weight: 500; }
footer .legal {
  width: 100%;
  border-top: 1px solid var(--line);
  margin-top: 6px;
  padding-top: 16px;
  font-size: 12px;
  color: var(--ink-faint);
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.toolcard .ticon { display: block; margin-bottom: 10px; }
.toolcard.soon .ticon { opacity: .55; }
.diagram { padding: 24px 20px 16px; }