:root {
  --bg: #f4f7fb;
  --panel: #fff;
  --text: #172033;
  --muted: #64748b;
  --line: #dbe4ef;
  --accent: #2563eb;
  --accent-dark: #1d4ed8;
  --soft: #eef5ff;
  --shadow: 0 18px 45px rgba(15, 23, 42, .1);
}

html[data-theme='dark'] {
  color-scheme: dark;
  --bg: #0b1220;
  --panel: #111827;
  --text: #e5edf8;
  --muted: #a7b4c7;
  --line: #293548;
  --accent: #60a5fa;
  --accent-dark: #93c5fd;
  --soft: #17243a;
  --shadow: 0 18px 45px rgba(0, 0, 0, .34);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--text);
  background: radial-gradient(circle at top left, rgba(37, 99, 235, .14), transparent 34rem), var(--bg);
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.6;
}
a { color: var(--accent-dark); }
a:focus-visible, summary:focus-visible, select:focus-visible {
  outline: 3px solid rgba(37, 99, 235, .34);
  outline-offset: 3px;
}
.shell { width: min(1120px, calc(100% - 36px)); margin-inline: auto; }
.skip-link {
  position: fixed;
  z-index: 20;
  top: 10px;
  left: 10px;
  padding: 9px 12px;
  border-radius: 9px;
  background: var(--text);
  color: var(--panel);
  transform: translateY(-160%);
}
.skip-link:focus { transform: translateY(0); }
.site-header {
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  backdrop-filter: blur(14px);
}
.header-inner {
  display: flex;
  min-height: 76px;
  align-items: center;
  gap: 24px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; }
.brand img { width: 52px; height: 52px; object-fit: contain; }
.brand span, .brand small { display: block; }
.brand small { color: var(--muted); font-size: 12px; }
.header-inner nav { display: flex; margin-left: auto; gap: 18px; }
.header-inner nav a { color: var(--muted); font-weight: 700; text-decoration: none; }
.header-inner nav a:hover { color: var(--accent); }
.theme-picker { display: inline-flex; align-items: center; gap: 7px; color: var(--muted); font-size: 13px; font-weight: 700; }
.theme-picker select { padding: 7px 9px; border: 1px solid var(--line); border-radius: 9px; color: var(--text); background: var(--panel); }
.breadcrumbs { display: flex; gap: 9px; padding-top: 26px; color: var(--muted); font-size: 13px; }
.hero { padding: 70px 0 60px; text-align: center; }
.eyebrow { margin: 0 0 8px; color: var(--accent); font-size: 12px; font-weight: 900; letter-spacing: .13em; text-transform: uppercase; }
h1, h2 { margin-top: 0; line-height: 1.12; letter-spacing: -.035em; }
h1 { margin-bottom: 22px; font-size: clamp(42px, 8vw, 76px); }
h2 { font-size: clamp(27px, 4vw, 40px); }
.answer { max-width: 790px; margin: 0 auto; color: var(--muted); font-size: clamp(18px, 2.5vw, 23px); }
.hero-actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; margin-top: 30px; }
.button { display: inline-flex; min-height: 46px; align-items: center; padding: 10px 18px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); color: var(--text); font-weight: 800; text-decoration: none; }
.button.primary { border-color: var(--accent); background: var(--accent); color: #fff; }
.button:hover { transform: translateY(-1px); box-shadow: 0 10px 24px rgba(15, 23, 42, .12); }
.section-heading { margin-bottom: 24px; text-align: center; }
.facts { padding: 42px; border: 1px solid var(--line); border-radius: 26px; background: var(--panel); box-shadow: var(--shadow); }
.facts dl { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; margin: 0; }
.facts dl > div { padding: 18px; border: 1px solid var(--line); border-radius: 16px; background: var(--soft); }
.facts dt { margin-bottom: 5px; color: var(--muted); font-size: 12px; font-weight: 900; letter-spacing: .06em; text-transform: uppercase; }
.facts dd { margin: 0; font-weight: 700; }
.content-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; padding: 54px 0; }
.content-grid article { padding: 28px; border: 1px solid var(--line); border-radius: 20px; background: var(--panel); }
.content-grid h2 { margin-bottom: 12px; font-size: 25px; }
.content-grid p { margin: 0 0 12px; color: var(--muted); }
.content-grid p:last-child { margin-bottom: 0; }
.faq { padding: 52px 0; }
.faq details { max-width: 850px; margin: 0 auto 10px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); }
.faq summary { padding: 17px 20px; cursor: pointer; font-weight: 850; }
.faq details p { margin: 0; padding: 0 20px 20px; color: var(--muted); }
.sources { margin-bottom: 70px; padding: 30px; border-radius: 22px; background: var(--soft); }
.sources h2 { font-size: 26px; }
.sources ul { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px 28px; margin-bottom: 0; padding-left: 20px; }
.site-footer { padding: 30px 0; border-top: 1px solid var(--line); background: var(--panel); }
.site-footer .shell { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 16px; }
.site-footer span { color: var(--muted); }
.site-footer nav { display: flex; flex-wrap: wrap; margin-left: auto; gap: 14px; }

@media (max-width: 780px) {
  .header-inner { flex-wrap: wrap; padding: 12px 0; }
  .header-inner nav { order: 3; width: 100%; margin-left: 0; overflow-x: auto; }
  .theme-picker { margin-left: auto; }
  .facts { padding: 24px; }
  .facts dl, .content-grid { grid-template-columns: 1fr; }
  .sources ul { grid-template-columns: 1fr; }
  .site-footer nav { width: 100%; margin-left: 0; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; }
}