:root {
  --bg: #ffffff;
  --bg-elev: rgba(255, 255, 255, 0.72);
  --bg-card: #f5f5f7;
  --border: #d2d2d7;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --accent: #0071e3;
  --accent-dim: #0077ed;
  --ok: #248a3d;
  --warn: #b25000;
  --skip: #6e6e73;
  --link: #0066cc;
  --link-hover: #0071e3;
  --radius: 18px;
  --radius-sm: 12px;
  --max: 980px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.47059;
  font-size: 17px;
  font-weight: 400;
  letter-spacing: -0.022em;
  min-height: 100vh;
}
a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; text-underline-offset: 0.15em; }
img { max-width: 100%; height: auto; }
.wrap { max-width: var(--max); margin: 0 auto; padding: 0 22px 64px; }
.site-header {
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  background: var(--bg-elev);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  position: sticky; top: 0; z-index: 40;
}
.site-header .inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 12px 22px;
  display: flex; flex-wrap: wrap; align-items: center; gap: 12px 28px;
}
.brand {
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.02em;
  font-size: 19px;
  text-decoration: none;
}
.brand:hover { text-decoration: none; color: var(--text); }
.brand span { color: var(--accent); }
.nav { display: flex; flex-wrap: wrap; gap: 8px 20px; font-size: 14px; font-weight: 400; }
.nav a { color: var(--muted); text-decoration: none; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--text); text-decoration: none; }
.badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: -0.01em;
  padding: 4px 10px;
  border-radius: 980px;
  background: var(--bg-card);
  color: var(--muted);
  border: none;
  text-transform: none;
}
.badge.req { color: var(--ok); background: #e4f8e9; }
.badge.opt { color: var(--warn); background: #fff1e5; }
.badge.skip { color: var(--skip); background: var(--bg-card); }
h1 {
  font-size: clamp(32px, 5vw, 48px);
  line-height: 1.08349;
  font-weight: 600;
  letter-spacing: -0.015em;
  margin: 28px 0 12px;
}
h2 {
  font-size: 28px;
  line-height: 1.14286;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 48px 0 16px;
  color: var(--text);
}
h3 {
  font-size: 21px;
  line-height: 1.19048;
  font-weight: 600;
  letter-spacing: -0.016em;
  margin: 24px 0 8px;
  color: var(--text);
}
.lead {
  color: var(--muted);
  font-size: 21px;
  line-height: 1.381;
  font-weight: 400;
  letter-spacing: -0.016em;
  margin: 0 0 20px;
  max-width: 36em;
}
.meta-line { font-size: 14px; color: var(--muted); margin-bottom: 28px; }
.tabs {
  display: flex; flex-wrap: wrap; gap: 8px;
  margin: 20px 0 24px;
}
.tab {
  appearance: none; border: none;
  background: var(--bg-card); color: var(--text);
  padding: 8px 16px; border-radius: 980px;
  cursor: pointer; font-size: 14px; font-weight: 500;
  font-family: inherit;
  transition: background 0.2s ease, color 0.2s ease;
}
.tab:hover { background: #e8e8ed; }
.tab.active { background: var(--text); color: #fff; }
.card-list { display: grid; gap: 12px; }
.card {
  background: var(--bg-card);
  border: none;
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: none;
}
.card .row { display: flex; flex-wrap: wrap; align-items: baseline; gap: 6px 12px; }
.card .num {
  font-weight: 600; color: var(--accent);
  min-width: 1.6rem;
  font-variant-numeric: tabular-nums;
}
.card .title { font-weight: 600; flex: 1; letter-spacing: -0.01em; }
.card .year { color: var(--muted); font-size: 15px; }
.card .why { margin: 8px 0 0; color: var(--muted); font-size: 15px; }
.card .notes { margin: 6px 0 0; font-size: 14px; color: var(--muted); }
.table-wrap {
  overflow-x: auto; margin: 20px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: #fff;
}
table { width: 100%; border-collapse: collapse; font-size: 15px; }
th, td { padding: 14px 16px; text-align: left; border-bottom: 1px solid var(--border); }
th {
  background: var(--bg-card);
  color: var(--muted);
  font-weight: 600;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}
tr:last-child td { border-bottom: none; }
tr:hover td { background: rgba(0, 0, 0, 0.02); }
.timeline {
  position: relative;
  margin: 24px 0 32px;
  padding-left: 22px;
  border-left: 2px solid var(--border);
}
.timeline .node {
  position: relative;
  margin: 0 0 22px;
  padding-left: 14px;
}
.timeline .node::before {
  content: "";
  position: absolute;
  left: -28px; top: 6px;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px #fff;
}
.timeline .node .when { font-size: 13px; color: var(--accent); font-weight: 600; }
.callout {
  background: var(--bg-card);
  border-left: none;
  padding: 18px 22px;
  margin: 20px 0;
  border-radius: var(--radius);
  color: var(--muted);
  font-size: 15px;
}
.callout strong { color: var(--text); }
.grid-2 {
  display: grid;
  gap: 16px;
  grid-template-columns: 1fr;
}
@media (min-width: 734px) {
  .grid-2 { grid-template-columns: 1fr 1fr; }
}
.panel {
  background: var(--bg-card);
  border: none;
  border-radius: var(--radius);
  padding: 28px 26px;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}
.panel:hover {
  box-shadow: var(--shadow);
  transform: scale(1.01);
}
.panel h3 { margin-top: 0; color: var(--text); }
.panel p { color: var(--muted); font-size: 15px; margin: 0 0 12px; }
.panel a { font-weight: 500; }
.faq details {
  background: var(--bg-card);
  border: none;
  border-radius: var(--radius-sm);
  margin: 10px 0;
  padding: 14px 18px;
}
.faq summary { cursor: pointer; font-weight: 600; letter-spacing: -0.01em; }
.faq details[open] summary { color: var(--accent); margin-bottom: 8px; }
.related {
  display: flex; flex-wrap: wrap; gap: 10px;
  margin: 16px 0 0;
}
.related a {
  display: inline-block;
  padding: 8px 16px;
  border: none;
  border-radius: 980px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  background: var(--bg-card);
  text-decoration: none;
  transition: background 0.2s ease;
}
.related a:hover { background: #e8e8ed; color: var(--text); text-decoration: none; }
.site-footer {
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  background: #f5f5f7;
  margin-top: 64px;
  padding: 40px 22px 48px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.5;
}
.site-footer .inner { max-width: var(--max); margin: 0 auto; }
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--text); }
.footer-links { display: flex; flex-wrap: wrap; gap: 8px 16px; margin: 12px 0 16px; font-size: 12px; }
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); border: 0;
}
.hidden { display: none !important; }
.path-note { font-size: 15px; color: var(--muted); margin: -8px 0 20px; }
.total { font-size: 15px; color: var(--text); margin: 8px 0 20px; }
.total strong { color: var(--accent); }