:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #1c2230;
  --muted: #5b6474;
  --border: #e2e5eb;
  --primary: #1f5eff;
  --primary-dark: #1546c4;
  --primary-soft: #eaf0ff;
  --ok: #0f8a4f;
  --ok-soft: #e6f6ee;
  --warn: #b25e00;
  --warn-soft: #fff4e5;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 4px 16px rgba(16, 24, 40, .05);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

a { color: var(--primary); }
a:hover { color: var(--primary-dark); }

img { max-width: 100%; height: auto; }

.container { max-width: 1040px; margin: 0 auto; padding: 0 16px; }
.narrow { max-width: 760px; }

/* Header */
.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between;
  gap: 16px; min-height: 60px; flex-wrap: wrap;
}
.logo {
  font-weight: 800; font-size: 1.2rem; text-decoration: none; color: var(--text);
  letter-spacing: -.02em;
}
.logo span { color: var(--primary); }
.nav { display: flex; gap: 18px; flex-wrap: wrap; }
.nav a { text-decoration: none; color: var(--muted); font-weight: 500; font-size: .95rem; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--primary); }

/* Hero */
.hero { padding: 56px 0 32px; }
.hero h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); line-height: 1.2; margin: 0 0 12px; letter-spacing: -.02em; }
.hero p { font-size: 1.15rem; color: var(--muted); margin: 0 0 24px; max-width: 640px; }

.btn {
  display: inline-block; background: var(--primary); color: #fff; text-decoration: none;
  padding: 12px 20px; border-radius: 10px; font-weight: 600; border: 0; cursor: pointer; font-size: 1rem;
}
.btn:hover { background: var(--primary-dark); color: #fff; }
.btn-secondary { background: var(--primary-soft); color: var(--primary); }
.btn-secondary:hover { background: #dbe5ff; color: var(--primary-dark); }

/* Cards */
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px; box-shadow: var(--shadow);
}
.card h2, .card h3 { margin-top: 0; font-size: 1.15rem; }
.card p { color: var(--muted); margin: 0 0 12px; }
a.card { text-decoration: none; color: inherit; display: block; transition: border-color .15s; }
a.card:hover { border-color: var(--primary); }
.card .tag { display: inline-block; font-size: .78rem; font-weight: 600; color: var(--primary); background: var(--primary-soft); padding: 2px 8px; border-radius: 99px; margin-bottom: 8px; }

section { padding: 24px 0; }
section > .container > h2 { font-size: 1.5rem; }

/* Article */
.article { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px 32px; margin: 28px auto; }
.article h1 { font-size: clamp(1.6rem, 3.5vw, 2.2rem); line-height: 1.25; margin-top: 0; letter-spacing: -.01em; }
.article h2 { margin-top: 2em; font-size: 1.4rem; }
.article h3 { margin-top: 1.5em; font-size: 1.15rem; }
.meta { color: var(--muted); font-size: .9rem; margin-bottom: 20px; }
.lead { font-size: 1.1rem; color: #333b4c; }
.breadcrumb { font-size: .88rem; color: var(--muted); margin: 20px 0 0; }
.breadcrumb a { color: var(--muted); }

table { border-collapse: collapse; width: 100%; margin: 16px 0; font-size: .95rem; }
.table-wrap { overflow-x: auto; }
th, td { border: 1px solid var(--border); padding: 10px 12px; text-align: left; vertical-align: top; }
th { background: var(--bg); }

.callout { border-left: 4px solid var(--primary); background: var(--primary-soft); padding: 14px 18px; border-radius: 0 10px 10px 0; margin: 20px 0; }
.callout.warn { border-color: var(--warn); background: var(--warn-soft); }
.callout.ok { border-color: var(--ok); background: var(--ok-soft); }
.callout p:last-child { margin-bottom: 0; }

.cta-box { background: var(--primary-soft); border: 1px solid #c9d7ff; border-radius: var(--radius); padding: 20px; margin: 28px 0; }
.cta-box h3 { margin-top: 0; }

.disclosure { font-size: .85rem; color: var(--muted); background: var(--bg); border: 1px dashed var(--border); padding: 10px 14px; border-radius: 8px; }

/* Tool */
.tool { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 24px 0; }
@media (max-width: 800px) { .tool { grid-template-columns: 1fr; } }

.field { margin-bottom: 16px; }
.field label { display: block; font-weight: 600; margin-bottom: 6px; font-size: .95rem; }
.field .hint { font-size: .82rem; color: var(--muted); margin-top: 4px; }
input[type="number"], select {
  width: 100%; padding: 11px 12px; font-size: 1rem; border: 1px solid #cfd4dc; border-radius: 8px;
  background: #fff; color: var(--text); font-family: inherit;
}
input[type="number"]:focus, select:focus { outline: 2px solid var(--primary); outline-offset: 1px; border-color: var(--primary); }
.radio-row { display: flex; gap: 8px; flex-wrap: wrap; }
.radio-row label { font-weight: 500; display: flex; align-items: center; gap: 6px; background: var(--bg); border: 1px solid var(--border); padding: 8px 12px; border-radius: 8px; cursor: pointer; }
.checkbox { display: flex; gap: 8px; align-items: flex-start; font-weight: 500 !important; cursor: pointer; }
.checkbox input { margin-top: 5px; }

.results { position: sticky; top: 80px; align-self: start; }
.big-number { font-size: 2.2rem; font-weight: 800; color: var(--ok); letter-spacing: -.02em; line-height: 1.1; }
.big-label { color: var(--muted); font-size: .9rem; margin-bottom: 16px; }
.result-lines { list-style: none; padding: 0; margin: 0; }
.result-lines li { display: flex; justify-content: space-between; gap: 12px; padding: 8px 0; border-bottom: 1px solid var(--border); font-size: .95rem; }
.result-lines li span:last-child { font-weight: 600; white-space: nowrap; }
.result-lines li.total { font-weight: 700; border-bottom: 0; }
.alerts .callout { margin: 12px 0 0; font-size: .92rem; }

.faq details { background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 12px 16px; margin-bottom: 10px; }
.faq summary { font-weight: 600; cursor: pointer; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); background: var(--surface); margin-top: 48px; padding: 28px 0; font-size: .9rem; color: var(--muted); }
.site-footer .container { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.site-footer a { color: var(--muted); margin-right: 14px; }

@media (max-width: 600px) {
  .article { padding: 20px 16px; border-radius: 0; border-left: 0; border-right: 0; }
  .hero { padding: 36px 0 20px; }
  body { font-size: 16px; }
}