/* ==========================================================================
   StatsCalc — shared design system
   Tokens: ink navy + one working blue + light blue surfaces.
   Type: Newsreader (headings, editorial/trust) + Inter (UI/body) + IBM Plex Mono (formulas & code, functional not decorative)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Newsreader:ital,opsz,wght@0,6..72,400;0,6..72,500;0,6..72,600;0,6..72,700;1,6..72,500&family=Inter:wght@400;500;600;700&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root {
  /* color */
  --ink: #10203D;
  --ink-soft: #4C5C7C;
  --ink-faint: #8091B4;
  --primary: #2554E8;
  --primary-dark: #17359E;
  --primary-tint: #E8EEFF;
  --surface: #F6F8FD;
  --surface-card: #FFFFFF;
  --surface-tint: #EEF3FF;
  --line: #DCE4F7;
  --line-strong: #B9CAF5;
  --result: #0B7A5B;
  --result-tint: #E4F6EF;

  /* type */
  --font-head: 'Newsreader', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'IBM Plex Mono', 'SFMono-Regular', Menlo, monospace;

  /* layout */
  --col-max: 1240px;
  --content-max: 700px;
  --rail-w: 300px;
  --radius: 10px;
  --radius-sm: 6px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--surface);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible, summary:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

h1, h2, h3, h4 {
  font-family: var(--font-head);
  color: var(--ink);
  line-height: 1.22;
  margin: 0 0 0.5em;
  font-weight: 600;
}
h1 { font-size: clamp(1.9rem, 1.5rem + 1.6vw, 2.7rem); font-weight: 700; }
h2 { font-size: clamp(1.4rem, 1.2rem + 0.8vw, 1.85rem); margin-top: 2.6em; }
h3 { font-size: 1.2rem; margin-top: 1.6em; }
p { margin: 0 0 1em; max-width: 68ch; }
.container p { color: var(--ink-soft); }

.container {
  max-width: var(--col-max);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- header ---------- */
.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--surface-card);
  position: sticky;
  top: 0;
  z-index: 40;
}
.site-header .bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 66px;
}
.brand {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--ink);
}
.brand span { color: var(--primary); }
.brand:hover { text-decoration: none; }

.main-nav { display: flex; align-items: center; gap: 28px; }
.main-nav a {
  color: var(--ink-soft);
  font-size: 0.95rem;
  font-weight: 500;
}
.main-nav a:hover { color: var(--primary); text-decoration: none; }
.nav-toggle { display: none; }

@media (max-width: 760px) {
  .main-nav { display: none; }
}

/* ---------- breadcrumb ---------- */
.breadcrumb {
  font-size: 0.85rem;
  color: var(--ink-faint);
  padding: 14px 0 0;
}
.breadcrumb a { color: var(--ink-faint); }
.breadcrumb a:hover { color: var(--primary); }

/* ---------- page grid: content + ad rail ---------- */
.page-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--rail-w);
  gap: 40px;
  padding: 28px 0 12px;
  align-items: start;
}
@media (max-width: 1000px) {
  .page-grid { grid-template-columns: 1fr; }
  .ad-rail { display: none; }
}

.content { max-width: var(--content-max); }

.ad-rail { position: sticky; top: 90px; }
.ad-slot {
  border: 1px solid var(--line);
  background: var(--surface-tint);
  border-radius: var(--radius-sm);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 10px;
  overflow: hidden;
}
.ad-slot.rail { width: 300px; min-height: 600px; margin-bottom: 20px; }
.ad-slot.bottom { width: 100%; min-height: 250px; margin: 8px 0 36px; }
.ad-slot .ad-label {
  align-self: flex-start;
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 8px;
}
.ad-slot ins.adsbygoogle { max-width: 100%; }

/* ---------- eyebrow / intro ---------- */
.lede { font-size: 1.08rem; color: var(--ink-soft); max-width: 62ch; }

/* ---------- calculator card ---------- */
.calc-card {
  background: var(--surface-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  margin: 22px 0 8px;
  box-shadow: 0 1px 2px rgba(16, 32, 61, 0.04);
}
.calc-card label {
  display: block;
  font-weight: 600;
  font-size: 0.92rem;
  margin-bottom: 8px;
  color: var(--ink);
}
.calc-card .hint {
  font-size: 0.83rem;
  color: var(--ink-faint);
  margin: -4px 0 12px;
}
.calc-card textarea {
  width: 100%;
  min-height: 96px;
  resize: vertical;
  padding: 12px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--ink);
  background: #fff;
}
.calc-card textarea:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-tint); }

.calc-row {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 16px;
}
.btn {
  appearance: none;
  border: none;
  cursor: pointer;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-sm);
  padding: 11px 22px;
  background: var(--primary);
  color: #fff;
  transition: background 0.15s ease;
}
.btn:hover { background: var(--primary-dark); }
.btn.secondary {
  background: transparent;
  color: var(--ink-soft);
  border: 1px solid var(--line-strong);
}
.btn.secondary:hover { background: var(--surface-tint); }

.option-group {
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
  margin: 2px 0 4px;
}
.option-group label {
  display: flex;
  align-items: center;
  gap: 7px;
  font-weight: 500;
  font-size: 0.92rem;
  color: var(--ink);
  cursor: pointer;
}
.option-group input[type="radio"] {
  accent-color: var(--primary);
  width: 16px;
  height: 16px;
  cursor: pointer;
}
.option-group .opt-note {
  display: block;
  font-weight: 400;
  font-size: 0.8rem;
  color: var(--ink-faint);
  margin-left: 23px;
}

.field-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 16px;
  margin-bottom: 4px;
}
.field-grid .field label {
  margin-bottom: 6px;
}
.calc-card input[type="number"],
.calc-card input[type="text"] {
  width: 100%;
  padding: 11px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--ink);
  background: #fff;
}
.calc-card input[type="number"]:focus,
.calc-card input[type="text"]:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-tint);
}
select.select-input {
  width: 100%;
  padding: 11px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.92rem;
  color: var(--ink);
  background: #fff;
}
select.select-input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-tint); }

.calc-error {
  color: #B3261E;
  font-size: 0.88rem;
  margin-top: 10px;
  display: none;
}

.results {
  margin-top: 22px;
  display: none;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 14px;
}
.results.show { display: grid; }
.result-tile {
  background: var(--result-tint);
  border: 1px solid #C7EBDC;
  border-radius: var(--radius-sm);
  padding: 14px 16px;
}
.result-tile .k {
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--result);
  font-weight: 600;
  margin-bottom: 4px;
}
.result-tile .v {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--ink);
}
.result-tile.primary { background: var(--primary); border-color: var(--primary); }
.result-tile.primary .k { color: #DCE6FF; }
.result-tile.primary .v { color: #fff; }

/* ---------- formula box ---------- */
.formula-box {
  background: var(--surface-tint);
  border-left: 3px solid var(--primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 18px 22px;
  margin: 18px 0;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  color: var(--ink);
  overflow-x: auto;
}
.formula-box .legend {
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--ink-soft);
  margin-top: 10px;
}

/* ---------- code block ---------- */
pre.code-block {
  background: #0F1B33;
  color: #E7EDFB;
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  line-height: 1.65;
  margin: 14px 0 22px;
}
pre.code-block .c { color: #7C93C9; }
pre.code-block .kw { color: #78A9FF; }
pre.code-block .fn { color: #8FE3C0; }

/* ---------- worked example table ---------- */
.steps { margin: 0; padding: 0; list-style: none; }
.steps li {
  display: flex;
  gap: 14px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}
.steps li:last-child { border-bottom: none; }
.steps .num {
  flex: none;
  width: 26px; height: 26px;
  border-radius: 50%;
  background: var(--primary-tint);
  color: var(--primary-dark);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.82rem;
  display: flex; align-items: center; justify-content: center;
}

table.data-table {
  border-collapse: collapse;
  width: 100%;
  margin: 14px 0 22px;
  font-size: 0.92rem;
}
table.data-table th, table.data-table td {
  border: 1px solid var(--line);
  padding: 8px 12px;
  text-align: center;
  font-family: var(--font-mono);
}
table.data-table th {
  background: var(--surface-tint);
  font-family: var(--font-body);
  font-weight: 600;
  color: var(--ink);
}

/* ---------- FAQ ---------- */
.faq-item {
  border-bottom: 1px solid var(--line);
}
.faq-item summary {
  cursor: pointer;
  padding: 16px 0;
  font-weight: 600;
  color: var(--ink);
  list-style: none;
  display: flex;
  justify-content: space-between;
  gap: 12px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: '+';
  color: var(--primary);
  font-size: 1.3rem;
  font-weight: 400;
  flex: none;
}
.faq-item[open] summary::after { content: '\2212'; }
.faq-item p { padding-bottom: 16px; margin: 0; color: var(--ink-soft); }

/* ---------- related calculators ---------- */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
  margin: 14px 0 8px;
}
.related-grid a {
  display: block;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--ink);
  font-size: 0.92rem;
  font-weight: 500;
  background: var(--surface-card);
}
.related-grid a:hover {
  border-color: var(--primary);
  color: var(--primary);
  text-decoration: none;
  background: var(--surface-tint);
}
.related-grid a.current {
  border-color: var(--primary);
  background: var(--primary-tint);
  color: var(--primary-dark);
}

/* ---------- footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  background: var(--surface-card);
  margin-top: 40px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr 1fr;
  gap: 36px;
  padding: 44px 0 28px;
}
@media (max-width: 700px) {
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
}
.footer-grid h4 {
  font-family: var(--font-body);
  font-size: 0.82rem;
  text-transform: none;
  letter-spacing: 0.01em;
  color: var(--ink);
  font-weight: 700;
  margin-bottom: 14px;
}
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: 9px; }
.footer-grid a { color: var(--ink-soft); font-size: 0.9rem; }
.footer-grid a:hover { color: var(--primary); }
.footer-about p { font-size: 0.9rem; color: var(--ink-soft); max-width: 34ch; }
.footer-bottom {
  border-top: 1px solid var(--line);
  padding: 18px 0;
  font-size: 0.82rem;
  color: var(--ink-faint);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

/* ---------- legal pages ---------- */
.legal .content { max-width: 760px; }
.legal h2 { margin-top: 2em; font-size: 1.3rem; }
.legal p, .legal li { color: var(--ink-soft); }
.legal .updated { color: var(--ink-faint); font-size: 0.88rem; margin-bottom: 2em; }
.legal ol.toc { padding-left: 20px; font-size: 0.92rem; }
.legal ol.toc li { margin-bottom: 6px; }