:root {
  --bg: #ffffff; --fg: #101828; --muted: #667085; --soft: #98a2b3;
  --accent: #2563eb; --accent-dark: #1d4ed8; --accent-soft: #eef4ff;
  --border: #e4e7ec; --card: #f8fafc;
  --good: #15803d; --good-bg: #e7f6ec;
  --warn-bg: #fff8e6; --warn-border: #f0d78a;
  --shadow-sm: 0 1px 2px rgba(16,24,40,.05);
  --shadow-md: 0 6px 16px -4px rgba(16,24,40,.10), 0 2px 4px -2px rgba(16,24,40,.04);
  --r: 12px;
}
* { box-sizing: border-box; }
body {
  margin: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--fg); background: var(--bg); line-height: 1.65; font-size: 16.5px;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; color: var(--accent-dark); }
header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  max-width: 860px; margin: 0 auto; padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  background: rgba(255,255,255,.92); backdrop-filter: blur(10px);
}
.brand { display: flex; align-items: center; gap: 9px; font-weight: 800; font-size: 1.25rem; color: var(--fg); letter-spacing: -0.02em; }
.brand:hover { text-decoration: none; }
.brand .mark {
  width: 28px; height: 28px; border-radius: 8px;
  display: inline-flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--accent), #1e40af); color: #fff;
  font-size: .85rem; font-weight: 800;
}
nav { display: flex; gap: 18px; font-size: 0.95rem; font-weight: 500; color: var(--muted); }
nav a { color: var(--muted); }
nav a:hover { color: var(--fg); text-decoration: none; }
main { max-width: 860px; margin: 0 auto; padding: 36px 20px 60px; }
h1 { font-size: 2.15rem; letter-spacing: -0.02em; margin: 0 0 12px; line-height: 1.2; }
h2 { font-size: 1.4rem; margin: 36px 0 12px; letter-spacing: -0.01em; }
h3 { font-size: 1.1rem; margin: 0 0 6px; }
p { margin: 10px 0; }
.hero { padding: 34px 0 12px; }
.lede { font-size: 1.15rem; color: var(--muted); max-width: 62ch; }
.badge {
  display: inline-block; background: var(--accent-soft); color: var(--accent-dark);
  font-size: .75rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase;
  padding: 5px 12px; border-radius: 99px; margin-bottom: 16px;
}
.steps { list-style: none; padding: 0; margin: 16px 0 0; display: grid; gap: 14px; counter-reset: step; }
.steps li {
  position: relative; background: var(--card); border: 1px solid var(--border);
  border-radius: var(--r); padding: 16px 18px 16px 60px;
}
.steps li::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: 16px; top: 17px;
  width: 28px; height: 28px; border-radius: 8px;
  background: var(--accent); color: #fff; font-weight: 800; font-size: .9rem;
  display: flex; align-items: center; justify-content: center;
}
.steps strong { display: block; margin-bottom: 2px; }
.steps p { margin: 2px 0 0; color: var(--muted); font-size: .95rem; }
.clusters { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; margin-top: 14px; }
.cluster { background: var(--card); border: 1px solid var(--border); border-radius: var(--r); padding: 18px; transition: transform .15s ease, box-shadow .15s ease; }
.cluster:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.cluster p { color: var(--muted); font-size: 0.92rem; margin: 4px 0 0; }
code { background: var(--card); border: 1px solid var(--border); border-radius: 5px; padding: 1px 6px; font-size: 0.9em; }
.trust { background: var(--card); border: 1px solid var(--border); border-radius: var(--r); padding: 20px 22px; }
.tool-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--r); padding: 20px; display: block; color: inherit; transition: transform .15s ease, box-shadow .15s ease, border-color .15s ease; }
.tool-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: #cdd6e4; text-decoration: none; }
.tool-card h3 { margin: 0 0 6px; font-size: 1.08rem; }
.tool-card p { color: var(--muted); font-size: .93rem; margin: 0 0 12px; }
.tool-card .go { font-weight: 650; font-size: .93rem; }
.tool-icon {
  width: 44px; height: 44px; border-radius: 11px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.35rem; background: var(--accent-soft); margin-bottom: 12px;
}
footer { border-top: 1px solid var(--border); padding: 26px 20px 40px; text-align: center; color: var(--muted); font-size: 0.9rem; background: var(--card); }
.foot-links { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; margin-bottom: 10px; }
footer p { margin: 6px 0 0; }
.crumbs { font-size: 0.88rem; color: var(--soft); margin-bottom: 8px; }
.crumbs a { color: var(--muted); }
.btn { display: inline-block; background: var(--accent); color: #fff; padding: 10px 20px; border-radius: 9px; font-weight: 650; margin-top: 10px; transition: background .12s ease; }
.btn:hover { background: var(--accent-dark); text-decoration: none; }
.calc { background: #fff; border: 1px solid var(--border); border-radius: var(--r); padding: 22px; margin: 22px 0; box-shadow: var(--shadow-md); }
.calc-fields { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 16px 18px; }
.calc-field { display: block; font-size: 0.92rem; font-weight: 600; }
.calc-field input[type="number"] {
  width: 100%; margin-top: 4px; padding: 9px 11px; font-size: 1rem;
  border: 1px solid var(--border); border-radius: 8px;
  font-variant-numeric: tabular-nums;
  transition: border-color .12s ease, box-shadow .12s ease;
}
.calc-field input[type="number"]:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px rgba(37,99,235,.14); }
.range-row { display: flex; align-items: center; gap: 10px; margin-top: 4px; }
.range-row input[type="range"] { flex: 1; accent-color: var(--accent); }
.calc-out { font-variant-numeric: tabular-nums; font-weight: 700; min-width: 64px; text-align: right; background: var(--card); border: 1px solid var(--border); border-radius: 7px; padding: 5px 9px; }
.calc-results { margin-top: 16px; }
.calc-big { font-size: 1.9rem; font-weight: 800; margin: 4px 0; letter-spacing: -0.02em; font-variant-numeric: tabular-nums; }
.calc-big span { font-size: 1rem; font-weight: 500; color: var(--muted); display: block; letter-spacing: 0; }
.calc-sub { color: var(--muted); font-size: 0.95rem; margin: 4px 0; }
.calc-table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 0.93rem; }
.calc-table th, .calc-table td { padding: 9px 10px; text-align: right; border-bottom: 1px solid var(--border); font-variant-numeric: tabular-nums; }
.calc-table th:first-child, .calc-table td:first-child { text-align: left; }
.calc-table th { font-size: .75rem; text-transform: uppercase; letter-spacing: .05em; color: var(--soft); border-bottom: 2px solid var(--border); }
.calc-table tr.best { background: var(--accent-soft); font-weight: 700; }
.calc-table tr.best td:first-child { border-left: 3px solid var(--accent); }
.calc-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 14px 0; }
.calc-opt { border: 1px solid var(--border); border-radius: var(--r); padding: 16px; background: var(--card); }
.calc-opt h4 { margin: 0 0 8px; }
.calc-opt p { margin: 0 0 8px; color: var(--muted); font-size: .92rem; }
.calc-opt strong { color: var(--fg); font-variant-numeric: tabular-nums; font-size: 1.02rem; }
.calc-opt.best { border-color: var(--accent); background: var(--accent-soft); box-shadow: 0 0 0 3px rgba(37,99,235,.12); }
.calc-note { color: var(--soft); font-size: 0.9rem; margin-top: 10px; }
.calc-warn { background: var(--warn-bg); border: 1px solid var(--warn-border); border-radius: 9px; padding: 12px 14px; margin-top: 10px; font-size: 0.95rem; color: #7a5b00; }
.calc-verdict { background: #eef2f6; border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: 9px; padding: 13px 16px; margin: 16px 0; font-size: .97rem; }
.calc-verdict.good { background: var(--good-bg); border-color: #bfe5c8; border-left-color: var(--good); }
.calc-verdict.bad { background: #fdecec; border-color: #f3c1c1; border-left-color: #b91c1c; }
/* charts */
.chart { margin: 18px 0 6px; }
.chart svg { width: 100%; height: auto; display: block; background: var(--card); border: 1px solid var(--border); border-radius: var(--r); }
.chart .cg { stroke: var(--border); stroke-width: 1; }
.chart .ct { fill: var(--soft); font-size: 11px; font-family: inherit; }
.legend { display: flex; gap: 16px; flex-wrap: wrap; margin-top: 10px; font-size: .87rem; color: var(--muted); }
.cl { display: inline-flex; align-items: center; gap: 7px; font-weight: 550; }
.cl i { width: 12px; height: 12px; border-radius: 4px; display: inline-block; }
.split-wrap { margin: 12px 0 4px; }
.split-bar { display: flex; height: 14px; border-radius: 7px; overflow: hidden; background: var(--border); }
.split-bar i { height: 100%; display: block; }
.assumptions { background: var(--card); border: 1px solid var(--border); border-radius: var(--r); padding: 16px 20px; margin: 22px 0; }
.assumptions ul { margin: 6px 0 2px; padding-left: 20px; }
.assumptions li { margin: 5px 0; color: var(--muted); font-size: 0.93rem; }
details.faq { border: 1px solid var(--border); border-radius: var(--r); padding: 6px 18px; margin: 10px 0; background: #fff; }
details.faq summary { font-weight: 600; cursor: pointer; padding: 10px 0; }
details.faq p { margin: 0 0 14px; color: var(--muted); }
.related { display: flex; gap: 10px; flex-wrap: wrap; margin: 14px 0; }
.related a { background: var(--card); border: 1px solid var(--border); border-radius: 99px; padding: 7px 15px; font-size: .9rem; font-weight: 550; }
.related a:hover { border-color: var(--accent); text-decoration: none; }
@media (max-width: 560px) {
  .calc-compare { grid-template-columns: 1fr; }
  .calc-fields { grid-template-columns: 1fr; }
  h1 { font-size: 1.7rem; }
}