/* CalculationPro — design system */

:root {
  --font-sans: "Instrument Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  --color-bg: #f8f9fc;
  --color-bg-elevated: #ffffff;
  --color-bg-subtle: #f1f2f7;
  --color-border: #e5e7ef;
  --color-text: #14161f;
  --color-text-muted: #5c6072;
  --color-text-faint: #9296a8;

  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-primary-soft: #eef0fe;
  --color-accent: #0ea5a4;
  --color-success: #16a34a;
  --color-danger: #dc2626;

  --shadow-sm: 0 1px 2px rgba(20, 22, 40, 0.04);
  --shadow-md: 0 6px 20px rgba(20, 22, 40, 0.06);
  --shadow-lg: 0 18px 44px rgba(20, 22, 40, 0.10);

  --radius-sm: 7px;
  --radius-md: 11px;
  --radius-lg: 16px;

  --header-h: 64px;
  --container-w: 1160px;
}

:root[data-theme="dark"] {
  --color-bg: #0e1015;
  --color-bg-elevated: #161923;
  --color-bg-subtle: #1b1f2c;
  --color-border: #292d3d;
  --color-text: #eceef5;
  --color-text-muted: #a7abbe;
  --color-text-faint: #6d7185;

  --color-primary: #8b83f6;
  --color-primary-hover: #a8a2f9;
  --color-primary-soft: #23264a;
  --color-accent: #2dd4bf;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.32);
  --shadow-lg: 0 18px 44px rgba(0, 0, 0, 0.45);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg: #0e1015;
    --color-bg-elevated: #161923;
    --color-bg-subtle: #1b1f2c;
    --color-border: #292d3d;
    --color-text: #eceef5;
    --color-text-muted: #a7abbe;
    --color-text-faint: #6d7185;

    --color-primary: #8b83f6;
    --color-primary-hover: #a8a2f9;
    --color-primary-soft: #23264a;
    --color-accent: #2dd4bf;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.32);
    --shadow-lg: 0 18px 44px rgba(0, 0, 0, 0.45);
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { line-height: 1.22; margin: 0 0 0.5em; font-weight: 700; letter-spacing: -0.015em; text-wrap: balance; }
h1 { font-size: clamp(1.65rem, 1.3rem + 1.5vw, 2.45rem); }
h2 { font-size: clamp(1.3rem, 1.15rem + 0.65vw, 1.65rem); }
h3 { font-size: 1.15rem; letter-spacing: -0.01em; }
p { margin: 0 0 1em; color: var(--color-text-muted); }
ul, ol { color: var(--color-text-muted); }

@media (prefers-reduced-motion: no-preference) {
  a, .btn, .cat-card, .calc-card, .theme-toggle, .nav-toggle, .field input, .field select, .field textarea {
    transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease, box-shadow 0.15s ease, transform 0.15s ease;
  }
}

.container {
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-h);
  display: flex;
  align-items: center;
  background: color-mix(in srgb, var(--color-bg-elevated) 90%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.site-header .container { display: flex; align-items: center; gap: 20px; width: 100%; }
.brand { display: flex; align-items: center; gap: 9px; font-weight: 700; font-size: 1.14rem; letter-spacing: -0.01em; color: var(--color-text); flex-shrink: 0; }
.brand:hover { text-decoration: none; }
.brand .brand-mark { width: 29px; height: 29px; border-radius: 8px; background: linear-gradient(135deg, var(--color-primary), var(--color-accent)); display: flex; align-items: center; justify-content: center; color: #fff; font-size: 14px; font-weight: 700; }
.brand .brand-pro { color: var(--color-accent); }

.main-nav { display: flex; align-items: center; gap: 2px; flex: 1; }
.main-nav a { color: var(--color-text-muted); font-weight: 600; font-size: 0.9rem; padding: 8px 11px; border-radius: var(--radius-sm); white-space: nowrap; }
.main-nav a:hover { background: var(--color-bg-subtle); text-decoration: none; color: var(--color-text); }

.header-search { position: relative; flex: 1; max-width: 300px; margin-left: auto; }
.header-search input {
  width: 100%; padding: 9px 14px 9px 36px; border-radius: 999px; border: 1px solid var(--color-border);
  background: var(--color-bg-subtle); color: var(--color-text); font-size: 0.88rem; font-family: inherit;
}
.header-search input:focus { outline: none; box-shadow: 0 0 0 3px var(--color-primary-soft); border-color: var(--color-primary); }
.header-search::before {
  content: ""; position: absolute; left: 12px; top: 50%; width: 14px; height: 14px; transform: translateY(-50%);
  background: var(--color-text-faint);
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M10 4a6 6 0 104.472 10.03l4.75 4.75a1 1 0 001.414-1.414l-4.75-4.75A6 6 0 0010 4zm-4 6a4 4 0 118 0 4 4 0 01-8 0z'/%3E%3C/svg%3E") center/contain no-repeat;
  mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M10 4a6 6 0 104.472 10.03l4.75 4.75a1 1 0 001.414-1.414l-4.75-4.75A6 6 0 0010 4zm-4 6a4 4 0 118 0 4 4 0 01-8 0z'/%3E%3C/svg%3E") center/contain no-repeat;
}
.search-results {
  position: absolute; top: calc(100% + 8px); left: 0; right: 0; background: var(--color-bg-elevated);
  border: 1px solid var(--color-border); border-radius: var(--radius-md); box-shadow: var(--shadow-lg);
  max-height: 360px; overflow-y: auto; display: none; z-index: 60;
}
.search-results.show { display: block; }
.search-results a { display: block; padding: 10px 14px; color: var(--color-text); font-size: 0.87rem; border-bottom: 1px solid var(--color-border); }
.search-results a:last-child { border-bottom: none; }
.search-results a:hover { background: var(--color-bg-subtle); text-decoration: none; }
.search-results .sr-cat { color: var(--color-text-faint); font-size: 0.74rem; text-transform: uppercase; letter-spacing: 0.05em; }
.search-empty { padding: 14px; color: var(--color-text-faint); font-size: 0.85rem; }

.theme-toggle, .nav-toggle {
  border: 1px solid var(--color-border); background: var(--color-bg-subtle); color: var(--color-text);
  width: 35px; height: 35px; border-radius: 999px; display: flex; align-items: center; justify-content: center;
  cursor: pointer; flex-shrink: 0; font-size: 15px;
}
.theme-toggle:hover, .nav-toggle:hover { border-color: var(--color-primary); color: var(--color-primary); }
.nav-toggle { display: none; border-radius: var(--radius-sm); }

/* ---------- Footer ---------- */
.site-footer { border-top: 1px solid var(--color-border); margin-top: 72px; padding: 48px 0 30px; background: var(--color-bg-elevated); }
.footer-grid { display: grid; grid-template-columns: 1.6fr repeat(3, 1fr); gap: 28px; }
.footer-col h4 { font-size: 0.82rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--color-text-faint); margin-bottom: 13px; font-weight: 600; }
.footer-col a { display: block; color: var(--color-text-muted); font-size: 0.89rem; padding: 4px 0; }
.footer-col a:hover { color: var(--color-primary); text-decoration: none; }
.footer-bottom { margin-top: 34px; padding-top: 22px; border-top: 1px solid var(--color-border); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; color: var(--color-text-faint); font-size: 0.81rem; }
.footer-bottom a { color: inherit; text-decoration: underline; text-underline-offset: 2px; }

/* ---------- Buttons & badges ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; border-radius: var(--radius-sm); padding: 11px 21px; font-weight: 600; font-size: 0.93rem; letter-spacing: -0.005em; border: 1px solid transparent; cursor: pointer; font-family: inherit; }
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-hover); }
.btn-outline { background: transparent; border-color: var(--color-border); color: var(--color-text); }
.btn-outline:hover { background: var(--color-bg-subtle); border-color: var(--color-text-faint); }
.chip { display: inline-block; padding: 4px 12px; border-radius: 999px; background: var(--color-primary-soft); color: var(--color-primary); font-size: 0.77rem; font-weight: 600; letter-spacing: 0.005em; }

/* ---------- Breadcrumbs ---------- */
.breadcrumbs { font-size: 0.84rem; color: var(--color-text-faint); margin: 18px 0; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.breadcrumbs a { color: var(--color-text-faint); }
.breadcrumbs a:hover { color: var(--color-primary); }
.breadcrumbs span[aria-current] { color: var(--color-text-muted); }

/* ---------- Hero ---------- */
.hero { padding: 60px 0 44px; text-align: center; }
.hero h1 { margin-bottom: 13px; }
.hero p.lede { max-width: 600px; margin: 0 auto 28px; font-size: 1.04rem; }
.hero-search { max-width: 560px; margin: 0 auto; position: relative; }
.hero-search input { width: 100%; padding: 15px 20px 15px 46px; border-radius: 999px; border: 1px solid var(--color-border); background: var(--color-bg-elevated); font-size: 1rem; font-family: inherit; color: var(--color-text); box-shadow: var(--shadow-md); }
.hero-search input:focus { outline: none; box-shadow: var(--shadow-md), 0 0 0 3px var(--color-primary-soft); border-color: var(--color-primary); }
.hero-search::before { content: ""; position: absolute; left: 18px; top: 50%; width: 18px; height: 18px; transform: translateY(-50%); background: var(--color-text-faint); -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M10 4a6 6 0 104.472 10.03l4.75 4.75a1 1 0 001.414-1.414l-4.75-4.75A6 6 0 0010 4zm-4 6a4 4 0 118 0 4 4 0 01-8 0z'/%3E%3C/svg%3E") center/contain no-repeat; mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M10 4a6 6 0 104.472 10.03l4.75 4.75a1 1 0 001.414-1.414l-4.75-4.75A6 6 0 0010 4zm-4 6a4 4 0 118 0 4 4 0 01-8 0z'/%3E%3C/svg%3E") center/contain no-repeat; }

/* ---------- Grids & cards ---------- */
.section { padding: 40px 0; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 20px; gap: 12px; flex-wrap: wrap; }
.section-head a { font-size: 0.87rem; font-weight: 600; }

.cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 14px; }
.cat-card { background: var(--color-bg-elevated); border: 1px solid var(--color-border); border-radius: var(--radius-md); padding: 22px; box-shadow: var(--shadow-sm); }
.cat-card:hover { border-color: var(--color-primary); text-decoration: none; box-shadow: var(--shadow-md); transform: translateY(-1px); }
.cat-card .cat-icon { width: 40px; height: 40px; border-radius: var(--radius-sm); background: var(--color-primary-soft); display: flex; align-items: center; justify-content: center; margin-bottom: 13px; color: var(--color-primary); }
.cat-card h3 { color: var(--color-text); margin-bottom: 4px; }
.cat-card p { font-size: 0.87rem; margin: 0; }

.calc-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 11px; }
.calc-card { background: var(--color-bg-elevated); border: 1px solid var(--color-border); border-radius: var(--radius-sm); padding: 14px 16px; font-weight: 600; font-size: 0.91rem; color: var(--color-text); }
.calc-card:hover { border-color: var(--color-primary); text-decoration: none; transform: translateY(-1px); box-shadow: var(--shadow-sm); }
.calc-card .cc-sub { display: block; font-weight: 500; font-size: 0.77rem; color: var(--color-text-faint); margin-top: 3px; }

.subgroup { margin-bottom: 32px; }
.subgroup h3 { color: var(--color-text-faint); font-size: 0.81rem; text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 13px; font-weight: 600; }

/* ---------- Calculator page layout ---------- */
.calc-layout { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 28px; align-items: start; padding: 10px 0 54px; }
.calc-main { min-width: 0; }
.calc-side { position: sticky; top: calc(var(--header-h) + 16px); display: flex; flex-direction: column; gap: 16px; }

.calc-card-box { background: var(--color-bg-elevated); border: 1px solid var(--color-border); border-radius: var(--radius-lg); padding: 28px; box-shadow: var(--shadow-sm); }
.calc-intro { color: var(--color-text-muted); margin-bottom: 22px; }

.field-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 17px; margin-bottom: 8px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: 0.85rem; font-weight: 600; color: var(--color-text); }
.field .field-hint { font-size: 0.78rem; color: var(--color-text-faint); margin-top: -3px; }
.field-input-wrap { position: relative; display: flex; align-items: center; }
.field input, .field select, .field textarea {
  width: 100%; padding: 11px 14px; border: 1px solid var(--color-border); border-radius: var(--radius-sm);
  background: var(--color-bg-subtle); color: var(--color-text); font-size: 0.97rem; font-family: inherit;
  font-variant-numeric: tabular-nums;
}
.field textarea { min-height: 84px; resize: vertical; font-variant-numeric: normal; }
.field input:focus, .field select:focus, .field textarea:focus { outline: none; box-shadow: 0 0 0 3px var(--color-primary-soft); border-color: var(--color-primary); background: var(--color-bg-elevated); }
.field .field-suffix { position: absolute; right: 14px; color: var(--color-text-faint); font-size: 0.84rem; pointer-events: none; }
.field input.has-suffix { padding-right: 44px; }
.field-input-wrap.has-inline-unit { gap: 8px; }
.field-input-wrap.has-inline-unit input { flex: 1 1 50%; min-width: 60px; width: 0; }

/* Unit select: shows only the short code (e.g. "m") when closed, but the
   underlying native <select> still opens with full unit names — the visible
   box is a styled overlay in front of a fully functional, invisible select,
   so keyboard nav / mobile native pickers / accessibility all keep working. */
.unit-select-wrap { position: relative; display: inline-flex; flex: 0 1 72px; width: 72px; max-width: 40%; }
.unit-select-display {
  display: flex; align-items: center; justify-content: space-between; gap: 4px; width: 100%;
  padding: 10px 8px; border: 1px solid var(--color-border); border-radius: var(--radius-sm);
  background: var(--color-bg-subtle); color: var(--color-text); font-size: 0.79rem; font-family: inherit;
  white-space: nowrap; overflow: hidden; pointer-events: none;
}
.unit-select-display::after { content: "\25BE"; color: var(--color-text-faint); flex-shrink: 0; font-size: 0.7em; }
.unit-select-wrap:focus-within .unit-select-display { outline: none; box-shadow: 0 0 0 3px var(--color-primary-soft); border-color: var(--color-primary); }
.unit-select-wrap select.unit-inline-select { position: absolute; inset: 0; width: 100%; height: 100%; opacity: 0; cursor: pointer; border: none; padding: 0; z-index: 1; }

.result-value-wrap { display: flex; align-items: center; gap: 8px; }
.result-value-wrap .unit-select-wrap { flex: 0 0 90px; width: 90px; max-width: none; }
.result-value-wrap .unit-select-display { font-size: 0.77rem; padding: 6px 6px; }

.calc-actions { display: flex; gap: 10px; margin-top: 20px; }

.results-box { margin-top: 24px; padding: 22px 24px; border-radius: var(--radius-md); background: var(--color-bg-elevated); border: 1px solid var(--color-border); border-top: 2px solid var(--color-primary); }
.result-row { display: flex; justify-content: space-between; align-items: baseline; padding: 9px 0; gap: 12px; }
.result-row + .result-row { border-top: 1px solid var(--color-border); }
.result-row .result-label { font-size: 0.89rem; color: var(--color-text-muted); font-weight: 500; }
.result-row .result-value { font-size: 1.18rem; font-weight: 700; color: var(--color-primary); text-align: right; font-variant-numeric: tabular-nums; }
.result-row.result-primary .result-value { font-size: 1.5rem; }

.explain { margin-top: 32px; padding-top: 28px; border-top: 1px solid var(--color-border); }
.explain h2 { font-size: 1.2rem; }
.explain p, .explain li { font-size: 0.95rem; }

.related-box { background: var(--color-bg-elevated); border: 1px solid var(--color-border); border-radius: var(--radius-md); padding: 19px; }
.related-box h4 { font-size: 0.81rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--color-text-faint); margin-bottom: 11px; font-weight: 600; }
.related-box a { display: block; padding: 7px 0; font-size: 0.89rem; font-weight: 600; border-bottom: 1px solid var(--color-border); }
.related-box a:last-child { border-bottom: none; }

/* ---------- Ad slots ---------- */
.ad-slot { position: relative; display: block; background: var(--color-bg-subtle); border: 1px dashed var(--color-border); border-radius: var(--radius-sm); overflow: hidden; margin: 0 auto; }
.ad-slot .adsbygoogle { display: block; width: 100%; height: 100%; }
.ad-fallback-label { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; color: var(--color-text-faint); font-size: 0.77rem; letter-spacing: 0.04em; text-transform: uppercase; pointer-events: none; }
.ad-slot ins.adsbygoogle[data-ad-status] ~ .ad-fallback-label { display: none; }
.ad-leaderboard { min-height: 280px; max-width: 728px; width: 100%; }
.ad-rectangle { min-height: 250px; max-width: 336px; width: 100%; }
.ad-skyscraper { min-height: 600px; width: 300px; }
.ad-inline-wrap { margin: 30px 0; }
.ad-top-wrap { padding: 14px 0 0; }

/* ---------- Static pages ---------- */
.prose { max-width: 780px; margin: 0 auto; padding: 32px 0 64px; }
.prose h2 { margin-top: 1.6em; }
.prose ul { padding-left: 1.2em; }

/* ---------- 404 ---------- */
.not-found { text-align: center; padding: 96px 0; }
.not-found .code { font-size: 4rem; font-weight: 700; color: var(--color-primary); letter-spacing: -0.02em; }

/* ---------- Responsive ---------- */
@media (max-width: 980px) {
  .calc-layout { grid-template-columns: 1fr; }
  .calc-side { position: static; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 760px) {
  .main-nav { display: none; }
  .header-search { display: none; }
  .nav-toggle { display: flex; }
  .calc-card-box { padding: 19px; }
}
@media (max-width: 520px) {
  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; }
  .result-row { flex-wrap: wrap; row-gap: 8px; }
  .result-value-wrap .unit-select-wrap { flex: 0 0 84px; width: 84px; }
}

/* Mobile drawer nav */
.mobile-nav { display: none; flex-direction: column; padding: 10px 20px 18px; border-bottom: 1px solid var(--color-border); background: var(--color-bg-elevated); }
.mobile-nav.show { display: flex; }
.mobile-nav a { padding: 10px 4px; color: var(--color-text); font-weight: 600; border-bottom: 1px solid var(--color-border); }
.mobile-nav a:last-child { border-bottom: none; }
.mobile-nav .header-search { display: block; max-width: none; margin: 0 0 10px; }

.skip-link { position: absolute; left: -999px; top: 0; background: var(--color-primary); color: #fff; padding: 10px 16px; border-radius: 0 0 8px 0; z-index: 100; }
.skip-link:focus { left: 0; }

.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }