/* ==========================================================================
   Calc Hives — shared stylesheet (mobile-first)
   -------------------------------------------------------------------------
   Paper:  #F6F7F9 (page bg)   #ECEEF2 (panel bg)
   Ink:    #12161C (primary)   #4A5160 (secondary)   #8A90A0 (faint)
   Accent: #3552F0 (indigo)    #263AC0 (indigo dark)  #F0A93E (amber, sparing)
   Line:   #D8DBE2 / #C0C4CE
   Type:   Space Grotesk (display) / Inter (body) / IBM Plex Mono (all numbers)
   ========================================================================== */

:root {
  --paper: #F6F7F9;
  --panel: #ECEEF2;
  --ink: #12161C;
  --ink-soft: #4A5160;
  --ink-faint: #8A90A0;
  --indigo: #3552F0;
  --indigo-dark: #263AC0;
  --amber: #F0A93E;
  --line: #D8DBE2;
  --line-strong: #C0C4CE;
  --radius: 10px;
  --max: 1120px;
  --header-h: 60px;
  --font-display: 'Space Grotesk', 'Arial Narrow', sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--indigo); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 2px solid var(--indigo);
  outline-offset: 2px;
}
button { font: inherit; }

.wrap { max-width: var(--max); margin: 0 auto; padding: 0 18px; }
@media (min-width: 640px) { .wrap { padding: 0 24px; } }

/* ==========================================================================
   Header — sticky, professional, collapses to a hamburger under 760px
   ========================================================================== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(246,247,249,0.92);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  max-width: var(--max); margin: 0 auto; padding: 0 18px;
  height: var(--header-h);
  display: flex; align-items: center; justify-content: space-between;
}
@media (min-width: 640px) { .header-inner { padding: 0 24px; } }

.brand {
  display: flex; align-items: center; gap: 9px;
  font-family: var(--font-display); font-weight: 700; font-size: 1.08rem;
  color: var(--ink); letter-spacing: -0.01em; flex-shrink: 0;
}
.brand-mark { width: 26px; height: 26px; flex-shrink: 0; }

.primary-nav { display: none; }
.primary-nav ul { list-style: none; display: flex; gap: 4px; margin: 0; padding: 0; }
.primary-nav a {
  display: block; padding: 8px 12px; border-radius: 6px;
  color: var(--ink-soft); font-size: 0.92rem; font-weight: 500;
}
.primary-nav a:hover, .primary-nav a[aria-current="page"] {
  color: var(--ink); background: var(--panel); text-decoration: none;
}

.menu-toggle {
  display: flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 8px;
  border: 1px solid var(--line-strong); background: #fff; cursor: pointer;
}
.menu-toggle svg { width: 20px; height: 20px; color: var(--ink); }

.mobile-nav {
  overflow: hidden;
  max-height: 0;
  background: #fff;
  transition: max-height 0.3s ease;
  will-change: max-height;
}
.mobile-nav.is-open {
  max-height: 80vh;
  overflow-y: auto;
  border-bottom: 1px solid var(--line);
  -webkit-overflow-scrolling: touch;
}
.mobile-nav ul { list-style: none; margin: 0; padding: 8px 18px 16px; }
.mobile-nav li + li { border-top: 1px solid var(--line); }
.mobile-nav a {
  display: block; padding: 13px 4px; color: var(--ink); font-weight: 500; font-size: 1rem;
}
.mobile-nav .nav-group-label {
  font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--ink-faint); padding: 14px 4px 4px;
}

@media (min-width: 760px) {
  .primary-nav { display: block; }
  .menu-toggle, .mobile-nav { display: none !important; }
}

/* ==========================================================================
   Breadcrumb / hero
   ========================================================================== */
.crumbs {
  font-size: 0.8rem; color: var(--ink-faint); padding: 14px 0 0;
  font-family: var(--font-mono); overflow-x: auto; white-space: nowrap;
}
.crumbs a { color: var(--ink-soft); }
.crumbs span[aria-current] { color: var(--ink); }

.hero { padding: 22px 0 8px; }
.eyebrow {
  font-family: var(--font-mono); font-size: 0.76rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--indigo); margin: 0 0 8px;
}
h1 {
  font-family: var(--font-display); font-size: clamp(1.6rem, 5.5vw, 2.6rem);
  line-height: 1.14; letter-spacing: -0.015em; margin: 0 0 10px; font-weight: 700;
}
.hero-sub { color: var(--ink-soft); max-width: 62ch; margin: 0 0 24px; font-size: 1rem; }

/* ==========================================================================
   Calculator layout — stacks on mobile, side-by-side from 900px
   ========================================================================== */
.calc-grid { display: grid; grid-template-columns: 1fr; gap: 16px; }
@media (min-width: 900px) {
  .calc-grid { grid-template-columns: 1.05fr 0.95fr; align-items: start; gap: 22px; }
}

.panel {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px;
}
@media (min-width: 640px) { .panel { padding: 24px; } }

.field { margin-bottom: 16px; }
.field:last-child { margin-bottom: 0; }
.field label {
  display: flex; justify-content: space-between; align-items: baseline; flex-wrap: wrap;
  gap: 4px 8px;
  font-size: 0.88rem; font-weight: 600; color: var(--ink); margin-bottom: 6px;
}
.field label .unit { font-family: var(--font-mono); color: var(--ink-faint); font-weight: 400; font-size: 0.78rem; }
.field input[type="text"],
.field input[type="number"],
.field select {
  width: 100%; padding: 13px 12px; border: 1px solid var(--line-strong);
  border-radius: 7px; font-family: var(--font-mono); font-size: 16px; /* 16px avoids iOS auto-zoom */
  background: var(--paper); color: var(--ink); min-height: 46px; /* touch target */
}
.field input:focus, .field select:focus { border-color: var(--indigo); }
.field-row { display: grid; grid-template-columns: 1fr; gap: 14px; }
@media (min-width: 480px) { .field-row { grid-template-columns: 1fr 1fr; } }
.range-hint { font-size: 0.78rem; color: var(--ink-faint); margin-top: 5px; font-family: var(--font-mono); }

.btn {
  appearance: none; border: none; cursor: pointer; border-radius: 7px;
  font-family: var(--font-body); font-weight: 600; font-size: 0.96rem;
  padding: 14px 18px; min-height: 48px;
}
.btn-primary { background: var(--indigo); color: #fff; width: 100%; margin-top: 4px; }
.btn-primary:hover { background: var(--indigo-dark); text-decoration: none; }
.btn-ghost { background: transparent; color: var(--ink-soft); border: 1px solid var(--line-strong); }

/* Result "receipt" panel — signature element */
.receipt {
  background: var(--ink); color: var(--paper); border-radius: var(--radius);
  padding: 22px 18px 18px; position: relative; overflow: hidden;
}
@media (min-width: 640px) { .receipt { padding: 26px 24px 20px; } }
.receipt::before {
  content: ""; position: absolute; top: 0; left: 0; right: 0; height: 4px;
  background: repeating-linear-gradient(90deg, var(--amber) 0 10px, transparent 10px 20px);
}
.receipt-label {
  font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.1em;
  text-transform: uppercase; color: #9BA3B8; margin: 6px 0 4px;
}
.receipt-figure {
  font-family: var(--font-mono); font-size: clamp(1.7rem, 8vw, 2.6rem);
  font-weight: 600; color: #fff; margin: 0 0 16px; word-break: break-word;
}
.receipt-line {
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap;
  font-family: var(--font-mono); font-size: 0.86rem; color: #C7CCDA;
  padding: 8px 0; border-top: 1px dashed #3A4050;
}
.receipt-line strong { color: #fff; font-weight: 600; }
.receipt-total {
  border-top: 1px solid #4A5160; margin-top: 4px; padding-top: 12px;
  font-family: var(--font-mono); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px;
  color: #fff; font-weight: 700; font-size: 1rem;
}

/* ==========================================================================
   Content sections
   ========================================================================== */
section.content { padding: 36px 0; border-top: 1px solid var(--line); }
@media (min-width: 640px) { section.content { padding: 46px 0; } }
section.content:first-of-type { margin-top: 32px; }
h2 {
  font-family: var(--font-display); font-size: clamp(1.25rem, 4vw, 1.5rem);
  letter-spacing: -0.01em; margin: 0 0 14px; font-weight: 700;
}
h3 { font-family: var(--font-display); font-size: 1.08rem; margin: 22px 0 8px; font-weight: 700; }
.content p { color: var(--ink-soft); max-width: 74ch; }
.content ul, .content ol { color: var(--ink-soft); max-width: 74ch; padding-left: 20px; }
.formula-box {
  background: var(--panel); border: 1px solid var(--line); border-radius: 8px;
  padding: 16px 16px; font-family: var(--font-mono); font-size: 0.88rem;
  overflow-x: auto; margin: 14px 0; color: var(--ink); line-height: 1.7;
}

.table-scroll { overflow-x: auto; margin: 16px 0; -webkit-overflow-scrolling: touch; }
.example-table { width: 100%; min-width: 420px; border-collapse: collapse; font-size: 0.9rem; }
.example-table th, .example-table td {
  text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line);
}
.example-table th { font-family: var(--font-mono); font-size: 0.74rem; text-transform: uppercase; color: var(--ink-faint); letter-spacing: 0.05em; }
.example-table td { font-family: var(--font-mono); color: var(--ink); }

/* FAQ */
.faq-item { border-bottom: 1px solid var(--line); padding: 16px 0; }
.faq-item h3 { margin: 0 0 8px; font-size: 1rem; }
.faq-item p { margin: 0; }

/* Related calculators */
.related-grid { display: grid; grid-template-columns: 1fr; gap: 10px; }
@media (min-width: 560px) { .related-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 900px) { .related-grid { grid-template-columns: repeat(3, 1fr); } }
.related-card {
  border: 1px solid var(--line); border-radius: 8px; padding: 14px 16px;
  background: #fff; font-size: 0.92rem; font-weight: 600; color: var(--ink);
  display: flex; align-items: center; gap: 10px; min-height: 48px;
}
.related-card:hover { border-color: var(--indigo); text-decoration: none; }
.related-card svg { width: 18px; height: 18px; flex-shrink: 0; color: var(--indigo); }
.related-card.is-soon { color: var(--ink-faint); }
.related-card.is-soon svg { color: var(--ink-faint); }
.soon-tag {
  margin-left: auto; font-family: var(--font-mono); font-size: 0.68rem;
  background: var(--panel); padding: 2px 6px; border-radius: 4px; color: var(--ink-faint);
}

/* ==========================================================================
   Footer — category navigation
   ========================================================================== */
.site-footer { border-top: 1px solid var(--line); margin-top: 20px; background: #fff; }
.footer-grid {
  display: grid; grid-template-columns: 1fr; gap: 28px;
  padding-top: 40px; padding-bottom: 24px;
}
@media (min-width: 640px) { .footer-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 900px) { .footer-grid { grid-template-columns: 1.2fr repeat(4, 1fr); gap: 20px; } }

.footer-brand .brand { margin-bottom: 10px; }
.footer-brand p { color: var(--ink-faint); font-size: 0.88rem; max-width: 32ch; margin: 0; }

.footer-col h4 {
  font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--ink-faint); margin: 0 0 12px; font-weight: 600;
}
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 9px; }
.footer-col a { color: var(--ink-soft); font-size: 0.9rem; }
.footer-col a:hover { color: var(--indigo); }
.footer-col .soon { color: var(--ink-faint); font-size: 0.9rem; }
.footer-col .soon .soon-tag { font-size: 0.65rem; margin-left: 6px; }

.footer-bottom {
  border-top: 1px solid var(--line); padding-top: 18px; padding-bottom: 18px;
  display: flex; flex-direction: column; gap: 10px;
}
@media (min-width: 640px) { .footer-bottom { flex-direction: row; justify-content: space-between; align-items: center; } }
.footer-bottom p { color: var(--ink-faint); font-size: 0.82rem; margin: 0; }
.footer-bottom nav { display: flex; gap: 16px; font-size: 0.82rem; flex-wrap: wrap; }
.footer-bottom nav a { color: var(--ink-soft); }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

/* ==========================================================================
   Charts — dependency-free inline SVG, rendered by LedgerChart (main.js)
   Series palette (validated, light surface): indigo / aqua / amber
   ========================================================================== */
.chart-card {
  margin-top: 18px; padding: 18px 16px 16px;
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
}
@media (min-width: 640px) { .chart-card { padding: 22px 22px 18px; } }
.chart-card .chart-title {
  font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--ink-faint); margin: 0 0 4px; font-weight: 600;
}
.chart-card .chart-note { color: var(--ink-faint); font-size: 0.82rem; margin: 2px 0 14px; }
.chart-svg { width: 100%; height: auto; display: block; overflow: visible; }
.chart-svg text { font-family: var(--font-body); }
.chart-svg .axis-label, .chart-svg .val-label { font-family: var(--font-mono); }

.chart-legend {
  list-style: none; margin: 14px 0 0; padding: 0;
  display: grid; grid-template-columns: 1fr; gap: 8px;
}
@media (min-width: 480px) { .chart-legend { grid-template-columns: 1fr 1fr; } }
.chart-legend li {
  display: flex; align-items: center; gap: 9px;
  font-size: 0.9rem; color: var(--ink-soft);
}
.chart-legend .swatch {
  width: 12px; height: 12px; border-radius: 3px; flex: none;
}
.chart-legend .lg-label { flex: 1; min-width: 0; }
.chart-legend .lg-value {
  font-family: var(--font-mono); font-weight: 600; color: var(--ink);
  font-variant-numeric: tabular-nums;
}
/* Donut centre figure */
.chart-svg.donut { max-width: 260px; margin: 0 auto; }
.chart-svg .donut-center-value { font-family: var(--font-display); font-weight: 700; fill: var(--ink); }
.chart-svg .donut-center-label { font-family: var(--font-mono); fill: var(--ink-faint); letter-spacing: 0.06em; }

/* Horizontal bar comparison */
.bar-chart { display: flex; flex-direction: column; gap: 14px; margin: 4px 0 2px; }
.bar-row .bar-head {
  display: flex; justify-content: space-between; align-items: baseline;
  gap: 12px; margin-bottom: 6px;
}
.bar-row .bar-name { font-size: 0.9rem; color: var(--ink-soft); }
.bar-row .bar-value {
  font-family: var(--font-mono); font-weight: 600; color: var(--ink);
  font-size: 0.92rem; font-variant-numeric: tabular-nums;
}
.bar-row .bar-track {
  height: 12px; background: var(--panel); border-radius: 6px; overflow: hidden;
}
.bar-row .bar-fill { height: 100%; border-radius: 6px; min-width: 2px; transition: width .25s ease; }