:root {
  --bg: #ffffff;
  --fg: #444444;
  --muted: #f5f5f5;
  --muted-fg: #949494;
  --primary: #013366;
  --primary-fg: #ffffff;
  --border: #d4d4d4;
  --card: #ffffff;
  --toc-bg: #f3f6fa;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
}

html.dark {
  --bg: #222222;
  --fg: #f5f5f5;
  --muted: #2a2a2a;
  --muted-fg: #b6b6b6;
  --primary: #8fb4e8;
  --primary-fg: #041428;
  --border: #737373;
  --card: #323232;
  --toc-bg: #1c2838;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  font-size: 18px;
  line-height: 1.55;
}
a { color: inherit; text-decoration: none; }
a:hover { text-decoration: underline; }
img, svg { display: block; }
button, input, select, textarea { font: inherit; color: inherit; }
[hidden] { display: none !important; }

.wrap { width: min(1180px, calc(100% - 24px)); margin: 0 auto; }
.wrap-narrow { width: min(980px, calc(100% - 32px)); margin: 0 auto; }
.wrap-prose { width: min(760px, calc(100% - 32px)); margin: 0 auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: #013366;
  border-bottom: 1px solid #01284f;
  color: #fff;
}
.header-bar {
  height: 65px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 8px;
  flex: 0 0 auto;
  text-decoration: none;
}
.brand svg { height: 28px; width: auto; }
.brand span {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
  line-height: 1;
}
.header-search { flex: 1 1 auto; min-width: 0; max-width: 500px; display: none; }
.header-actions { margin-left: auto; display: flex; align-items: center; gap: 4px; }
.nav-desk { display: none; position: relative; }
.icon-btn, .menu-btn {
  height: 40px;
  min-width: 40px;
  border: 0;
  background: transparent;
  border-radius: 16px;
  cursor: pointer;
  display: grid;
  place-items: center;
}
.icon-btn:hover, .menu-btn:hover, .calc-menu summary:hover { background: var(--muted); }
.calc-menu summary {
  list-style: none;
  cursor: pointer;
  border-radius: 16px;
  padding: 8px 12px;
  font-size: 15px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 4px;
}
.calc-menu summary::-webkit-details-marker { display: none; }
.calc-menu[open] summary { background: var(--muted); }
.calc-pop {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  z-index: 50;
  width: 248px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 6px;
  box-shadow: var(--shadow);
}
.calc-pop a, .mobile-panel a.cat-link {
  display: flex;
  align-items: center;
  gap: 10px;
  border-radius: 8px;
  padding: 7px 10px;
  font-size: 15px;
  font-weight: 500;
  line-height: 1.2;
  text-decoration: none;
}
.calc-pop a svg, .mobile-panel a.cat-link svg, .link-list a svg {
  width: 20px;
  height: 20px;
  min-width: 20px;
  flex: 0 0 20px;
  color: var(--primary);
}
.calc-pop a:hover, .mobile-panel a.cat-link:hover { background: var(--muted); }
.mobile-panel { display: none; border-top: 1px solid rgba(255, 255, 255, 0.16); padding: 16px; background: #013366; }
.mobile-panel.open { display: block; }
.mobile-panel .cat-link { font-weight: 500; color: #fff; }
.site-header .brand span,
.site-header .calc-menu > summary,
.site-header .icon-btn,
.site-header .menu-btn,
.site-header .lang-menu > summary { color: #fff; }
.lang-menu { position: relative; }
.lang-menu > summary {
  list-style: none;
  cursor: pointer;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  padding: 8px 10px;
  border-radius: 16px;
}
.lang-menu > summary::-webkit-details-marker { display: none; }
.lang-pop {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  z-index: 60;
  min-width: 196px;
  background: var(--card);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 6px;
  box-shadow: var(--shadow);
}
html[dir="rtl"] .lang-pop { right: auto; left: 0; }
.lang-pop a {
  display: block;
  padding: 7px 10px;
  border-radius: 8px;
  font-size: 15px;
  color: var(--fg);
  text-decoration: none;
  font-weight: 500;
}
.lang-pop a[aria-current="true"] { color: var(--primary); font-weight: 700; }
.lang-pop a:hover { background: var(--muted); text-decoration: none; }
.site-header .brand svg path { fill: #fff; }
.site-header .icon-btn:hover,
.site-header .menu-btn:hover,
.site-header .calc-menu summary:hover,
.site-header .calc-menu[open] summary,
.site-header .lang-menu > summary:hover,
.site-header .lang-menu[open] > summary { background: rgba(255, 255, 255, 0.12); }
.site-header .search input { background: #fff; color: #222; border-color: transparent; }
.site-header .search svg.mag { color: #013366; }
.site-header .suggest,
.site-header .calc-pop,
.site-header .calc-pop a { color: var(--fg); }
.site-header .mobile-panel a.cat-link { color: #fff; }
.site-header .mobile-panel a.cat-link svg { color: #fff; }
.site-header .mobile-panel a.cat-link:hover { background: rgba(255, 255, 255, 0.12); }
.site-footer .brand svg path { fill: #013366; }
html.dark .site-footer .brand svg path { fill: #8fb4e8; }

.search { position: relative; }
.search input {
  width: 100%;
  height: 40px;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 0 14px 0 40px;
  background: var(--bg);
}
.search.large input { height: 48px; border-radius: 16px; }
.search svg.mag {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted-fg);
}
.suggest {
  position: absolute;
  left: 0;
  right: 0;
  top: calc(100% + 6px);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  z-index: 30;
  max-height: 320px;
  overflow: auto;
  padding: 8px;
}
.suggest p { margin: 4px 8px 8px; font-size: 13px; color: var(--muted-fg); }
.suggest a, .suggest button {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: 0;
  border-radius: 10px;
  padding: 8px 10px;
  cursor: pointer;
  font-size: 15px;
  text-decoration: none;
}
.suggest a:hover, .suggest button:hover { background: var(--muted); }

.hero { text-align: center; padding: 48px 0 24px; }
.hero h1, .page-title {
  margin: 0;
  color: var(--primary);
  font-weight: 600;
  font-size: 35px;
  line-height: 1.15;
}
.kicker {
  margin: 16px auto 0;
  max-width: 640px;
  font-size: 18px;
  font-weight: 600;
}
.hero .search { margin: 32px auto 0; max-width: 640px; text-align: left; }

.cat-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.cat-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px 16px 24px;
  text-decoration: none;
  color: var(--fg);
}
.cat-card:hover { border-color: var(--fg); text-decoration: none; }
.cat-card svg { width: 75px; height: 75px; color: var(--primary); opacity: 0.8; }
.cat-card span { margin-top: 8px; font-size: 16px; font-weight: 500; }
.discover { text-align: center; margin: 32px 0 0; }
.discover a { color: var(--primary); font-weight: 600; }

.panel {
  margin-top: 48px;
  background: var(--muted);
  border-radius: 16px;
  padding: 40px 24px;
  text-align: center;
}
.panel h2, .section-title, .prose h2 {
  margin: 0;
  color: var(--primary);
  font-size: 26px;
  font-weight: 600;
  line-height: 1.2;
}
.panel p { max-width: 640px; margin: 16px auto 0; }
.chips { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px 40px; margin-top: 32px; font-weight: 600; color: var(--muted-fg); }

.featured { text-align: center; padding: 56px 0 24px; }
.eyebrow { margin: 0; font-size: 18px; font-weight: 600; letter-spacing: 0.04em; text-transform: uppercase; }
.featured .lead, .about p { margin: 24px 0 0; }
.featured .lead { text-align: left; }
.about { text-align: center; padding: 24px 0 56px; }
.about p { text-align: left; }
.about a, .lead a, .crumb a { color: var(--primary); }

.pop-grid {
  display: grid;
  gap: 16px;
  margin-top: 32px;
  text-align: left;
}
.pop-card { border: 1px solid var(--border); border-radius: 16px; padding: 16px 20px; }
.pop-card h3 { margin: 0; font-size: 18px; display: flex; align-items: center; gap: 8px; }
.pop-card h3 svg { width: 20px; height: 20px; color: var(--primary); }
.pop-card ul { list-style: none; margin: 12px 0 0; padding: 0; display: grid; gap: 8px; }
.pop-card li a { display: flex; justify-content: space-between; gap: 12px; font-size: 14px; text-decoration: none; }
.pop-card li a:hover { color: var(--primary); }
.see-all { display: inline-block; margin-top: 12px; color: var(--primary); font-size: 14px; font-weight: 600; }

.site-footer { border-top: 1px solid var(--border); padding: 28px 16px 40px; text-align: center; }
.site-footer .brand { justify-content: center; }
.foot-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px 18px; margin-top: 12px; font-size: 15px; }
.fine { color: var(--muted-fg); font-size: 14px; margin-top: 12px; }

.crumb { font-size: 14px; color: var(--muted-fg); margin: 0 0 12px; }
.page-head { padding: 28px 0 8px; }
.intro { margin: 12px 0 0; max-width: 720px; }

.calc-layout { display: grid; gap: 28px; padding-bottom: 48px; }
.calc-card, .result-card, .writeup, .section-block {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--card);
  padding: 20px;
}
.fields { display: grid; gap: 14px; }
.field label { display: block; font-size: 16px; font-weight: 500; margin-bottom: 6px; }
.control { display: flex; gap: 8px; }
.control input, .control select, .control textarea, .solo {
  width: 100%;
  min-height: 40px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--bg);
  padding: 8px 12px;
}
.control select { max-width: 140px; }
.control select.unit { max-width: none; }
a.btn { display: inline-flex; align-items: center; text-decoration: none; }
.control textarea, textarea.solo { min-height: 96px; resize: vertical; }
.calc-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.btn {
  height: 40px;
  border: 0;
  border-radius: 16px;
  padding: 0 18px;
  background: var(--primary);
  color: var(--primary-fg);
  font-weight: 700;
  cursor: pointer;
}
.btn.ghost { background: transparent; color: var(--primary); border: 1px solid var(--border); }
.eq {
  height: 40px;
  width: 48px;
  border: 0;
  border-radius: 16px;
  background: var(--primary);
  color: #fff;
  font-size: 22px;
  font-weight: 700;
  cursor: pointer;
}
.len-row { display: flex; gap: 8px; }
.len-row input { flex: 1; }

.result-card { border-color: #949494; text-align: center; }
.result-row { padding: 8px 0; }
.result-row .rl { font-size: 16px; color: var(--muted-fg); }
.result-row .rv { font-size: 22px; font-weight: 600; }
.result-row.em .rv { font-size: 28px; color: var(--primary); }
.note, .hint { color: var(--muted-fg); font-size: 15px; }
.writeup h2 { font-size: 28px; text-align: left; margin: 28px 0 8px; }
.writeup h2:first-child { margin-top: 0; }
.page-title[id], .writeup h2[id], .writeup h3[id] { scroll-margin-top: 84px; }
.on-page {
  margin: 0 0 22px;
  padding: 16px 18px 12px;
  background: var(--toc-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
}
.on-page-label { margin: 0 0 8px; font-size: 22px; font-weight: 700; color: var(--primary); }
.on-page ul { margin: 0; }
.on-page li { margin: 4px 0; }
.writeup p, .writeup li { font-size: 18px; }
.writeup a { color: var(--primary); text-decoration: underline; text-underline-offset: 3px; }
.writeup a:hover { text-decoration-thickness: 2px; }
.writeup ul, .writeup ol { padding-left: 1.25em; margin: 8px 0 0; }
.writeup li { margin: 6px 0; }
.writeup figure { margin: 18px 0; }
.writeup figure img { width: 100%; max-width: 560px; height: auto; display: block; background: #fff; border: 1px solid var(--border); border-radius: 12px; }
.writeup figcaption { margin-top: 8px; font-size: 15px; color: var(--muted-fg); }

.section-block { margin: 16px 0; }
.section-block h2 { font-size: 22px; margin-bottom: 8px; }
.link-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.link-list a { display: flex; justify-content: space-between; gap: 12px; padding: 6px 0; text-decoration: none; border-bottom: 1px solid transparent; }
.link-list a:hover { color: var(--primary); }

.timer-face {
  font-size: 56px;
  font-weight: 700;
  color: var(--primary);
  text-align: center;
  letter-spacing: 0.04em;
  margin: 8px 0 16px;
}
.clock-face { font-size: 42px; font-weight: 700; color: var(--primary); text-align: center; }

@media (min-width: 700px) {
  .brand svg { height: 35px; }
  .brand span { font-size: 30px; }
  .header-search { display: block; }
  .nav-desk { display: block; }
  .menu-btn { display: none; }
  .hero h1, .page-title { font-size: 50px; }
  .kicker, .eyebrow { font-size: 20px; }
  .cat-grid { grid-template-columns: repeat(3, 1fr); }
  .cat-card svg { width: 75px; height: 75px; }
  .panel h2, .section-title, .prose h2 { font-size: 35px; }
  .writeup h2 { font-size: 28px; }
  .featured .lead, .about p { text-align: center; }
  .pop-grid { grid-template-columns: repeat(2, 1fr); }
  .fields.two { grid-template-columns: 1fr 1fr; }
  .calc-layout { grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr); align-items: start; }
  .calc-layout .writeup { grid-column: 1 / -1; }
}
@media (min-width: 1020px) {
  .cat-grid { grid-template-columns: repeat(4, 1fr); }
  .pop-grid { grid-template-columns: repeat(3, 1fr); }
}

.rate-card {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 16px;
  margin-top: 4px;
}
.rate-label { margin: 0; font-weight: 700; }
.rate-stars { display: flex; gap: 4px; }
.rate-stars button {
  width: 36px;
  height: 36px;
  padding: 4px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
}
.rate-stars button[aria-pressed="true"] { background: rgba(224, 161, 0, 0.16); }
.rate-stars svg { width: 28px; height: 28px; }
.rate-meta { margin: 0; color: var(--muted-fg); font-size: 15px; }
.rate-meta strong { color: var(--fg); font-size: 18px; }

.share-rail {
  position: fixed;
  z-index: 35;
  top: 50%;
  left: 12px;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
html[dir="rtl"] .share-rail { left: auto; right: 12px; }
.share-rail a, .share-rail button {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 12px;
  padding: 0;
  cursor: pointer;
  text-decoration: none;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.16);
}
.share-rail svg { width: 22px; height: 22px; }
.share-rail .copied { outline: 2px solid var(--primary); }
@media (max-width: 800px) {
  .share-rail {
    top: auto;
    bottom: 0;
    left: 0;
    right: 0;
    transform: none;
    flex-direction: row;
    justify-content: center;
    gap: 6px;
    padding: 8px 8px calc(8px + env(safe-area-inset-bottom));
    background: var(--card);
    border-top: 1px solid var(--border);
  }
  html[dir="rtl"] .share-rail { left: 0; right: 0; }
  body.has-share { padding-bottom: 68px; }
}