:root {
  --bg: #ffffff;
  --text: #1b2430;
  --muted: #586374;
  --line: #dbe2ea;
  --accent: #0f766e;
  --accent-strong: #115e59;
  --calc-bg: #0f3b38;
  --calc-text: #e8f3f1;
  --calc-muted: #a6c6c1;
  --calc-field: #ffffff;
  --calc-field-text: #1b2430;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12171d;
    --text: #e4e9ef;
    --muted: #9aa6b4;
    --line: #2a333e;
    --accent: #2bb3a3;
    --accent-strong: #5fd0c2;
    --calc-bg: #0c2a28;
    --calc-text: #e3f1ef;
    --calc-muted: #8fb5af;
    --calc-field: #18211f;
    --calc-field-text: #e4e9ef;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

a { color: var(--accent); }
a:hover { color: var(--accent-strong); }

h1, h2, h3 { line-height: 1.2; margin: 0 0 .6em; }
h1 { font-size: 2.3rem; letter-spacing: -.01em; }
h2 { font-size: 1.6rem; }
h3 { font-size: 1.1rem; }

.wrap { max-width: 1040px; margin: 0 auto; padding: 0 20px; }

.top { border-bottom: 1px solid var(--line); }
.top__in {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px 24px;
  padding-top: 14px;
  padding-bottom: 14px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
}
.brand:hover { color: var(--text); }
.brand__icon { width: 28px; height: 28px; fill: var(--accent); flex: none; }
.nav { display: flex; flex-wrap: wrap; gap: 6px 20px; }
.nav a { color: var(--muted); text-decoration: none; font-size: .95rem; }
.nav a:hover { color: var(--accent); }

section { scroll-margin-top: 16px; }

.intro { padding-top: 48px; padding-bottom: 36px; }
.lead { font-size: 1.15rem; max-width: 46em; margin: 0 0 .8em; }
.upd { color: var(--muted); margin: 0; font-size: .95rem; }

.calc { background: var(--calc-bg); color: var(--calc-text); padding: 40px 0; margin-bottom: 48px; }
.calc__in { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 40px; }
.calc h2 { color: #fff; }
.field { display: block; margin-bottom: 6px; color: var(--calc-muted); }
.input {
  width: 100%;
  max-width: 220px;
  padding: 10px 12px;
  border: 1px solid transparent;
  border-radius: 6px;
  background: var(--calc-field);
  color: var(--calc-field-text);
  font: inherit;
  font-size: 1.1rem;
}
.input:focus { outline: 2px solid var(--accent); outline-offset: 2px; }
.kind { border: 0; padding: 0; margin: 22px 0 18px; }
.kind legend { padding: 0; margin-bottom: 8px; color: var(--calc-muted); }
.kind label {
  display: block;
  padding: 10px 12px;
  margin-bottom: 6px;
  border: 1px solid rgba(255, 255, 255, .22);
  border-radius: 6px;
  cursor: pointer;
}
.kind label:has(input:checked) { border-color: #fff; background: rgba(255, 255, 255, .08); }
.kind input, .check input { margin: 0 8px 0 0; accent-color: var(--accent); }
.check { display: flex; align-items: center; cursor: pointer; }
.calc__out { border-left: 1px solid rgba(255, 255, 255, .18); padding-left: 40px; }
.calc__label { margin: 0; color: var(--calc-muted); font-size: .95rem; }
.calc__sum { margin: 2px 0 18px; font-size: 2rem; font-weight: 700; font-variant-numeric: tabular-nums; color: #fff; }
.calc__sum--sub { font-size: 1.5rem; }
.calc__term { margin: 2px 0 18px; font-size: 1.25rem; font-weight: 600; }
.calc__note { margin: 0; color: var(--calc-muted); font-size: .9rem; }

.sect-lead { color: var(--muted); max-width: 46em; margin: 0 0 24px; }
.groups { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 28px 40px; margin-bottom: 56px; }
.group h3 { padding-bottom: 8px; border-bottom: 2px solid var(--accent); margin-bottom: 0; }
table { width: 100%; border-collapse: collapse; font-size: .95rem; }
th { text-align: left; font-weight: 600; color: var(--muted); font-size: .85rem; padding: 8px 8px 6px 0; }
td { padding: 7px 8px 7px 0; border-bottom: 1px solid var(--line); vertical-align: top; }
th:nth-child(2), td:nth-child(2) { width: 3.5em; color: var(--muted); }
th:last-child, td:last-child { text-align: right; padding-right: 0; white-space: nowrap; font-variant-numeric: tabular-nums; }

.factors { list-style: none; padding: 0; margin: 0 0 56px; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px 40px; }
.factors li { border-left: 3px solid var(--accent); padding-left: 14px; }
.factors strong { display: block; margin-bottom: 2px; }

.faq { margin-bottom: 56px; }
.faq details { border-bottom: 1px solid var(--line); padding: 12px 0; max-width: 52em; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq details p { margin: 10px 0 4px; color: var(--muted); }

.foot { border-top: 1px solid var(--line); padding: 24px 0 32px; color: var(--muted); font-size: .9rem; }
.foot p { margin: 0 0 6px; max-width: 52em; }

@media (max-width: 760px) {
  h1 { font-size: 1.8rem; }
  .intro { padding-top: 32px; padding-bottom: 28px; }
  .calc__in, .groups, .factors { grid-template-columns: minmax(0, 1fr); }
  .calc__out { border-left: 0; padding-left: 0; border-top: 1px solid rgba(255, 255, 255, .18); padding-top: 24px; }
  .calc__sum { font-size: 1.7rem; }
}