* { box-sizing: border-box; }
html { min-width: 280px; }
body { margin: 0; min-height: 100vh; min-height: 100svh; display: flex; flex-direction: column; }
a { color: inherit; text-decoration-color: var(--accent); text-underline-offset: .22em; }
a:hover { color: var(--accent); }
a:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 6px; }
button { font: inherit; }
button[hidden] { display: none; }
p { margin: 0; }
.container { width: 100%; max-width: var(--max-width); margin-inline: auto; padding-inline: clamp(22px, 5vw, var(--gutter)); }
.site-header { display: grid; grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr); align-items: center; gap: var(--stack-md); padding-block: 26px; }
.brand { font-family: var(--font-body); font-weight: 600; font-size: 19px; letter-spacing: -.04em; text-decoration: none; }
.euler { justify-self: center; color: var(--accent); font-family: var(--font-display); font-size: 19px; font-weight: 500; font-style: italic; line-height: 1; white-space: nowrap; }
.euler sup { font-size: .7em; }
.theme-toggle { justify-self: end; color: var(--ink-soft); background: none; border: 1px solid var(--rule); padding: 8px 12px; font-size: 13px; cursor: pointer; white-space: nowrap; }
.theme-toggle:hover { color: var(--ink); border-color: var(--ink-soft); }
main { flex: 1; padding-bottom: var(--section-pad); }
.intro { padding-block: clamp(42px, 8vw, var(--section-pad)) 0; border-top: 0; margin-bottom: var(--stack-xl); }
.intro .display-xl { font-size: clamp(38px, 6vw, 72px); overflow-wrap: break-word; }
.intro .lede { margin-top: var(--stack-md); }
.intro .gloss { margin-bottom: var(--stack-sm); }
.directory { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--stack-md) var(--stack-xl); padding-block: 0; border-top: 0; }
.directory-row { padding-block: var(--stack-md); border-top: 1px solid var(--rule); text-decoration: none; }
.directory-row p { margin-top: var(--stack-sm); color: var(--ink-soft); font-size: 16px; max-width: 40ch; }
.directory-row .display-md { display: flex; align-items: baseline; justify-content: space-between; gap: var(--stack-sm); }
.directory-row:hover .display-md { color: var(--accent); }
.pending .display-md { color: var(--ink-soft); }
.pending:hover .display-md { color: var(--ink-soft); }
.arrow { color: var(--accent); font-family: var(--font-body); font-size: 22px; }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 6px 12px; margin-top: var(--stack-lg); color: var(--ink-soft); font-size: 14px; }
.breadcrumbs + .intro { padding-top: var(--stack-lg); }
.course-entry { max-width: 740px; }
.course-entry .display-lg { margin-block: var(--stack-sm) var(--stack-md); }
.course-entry .display-lg a { text-decoration: none; }
.course-entry .body { max-width: 58ch; }
.text-link { display: inline-flex; align-items: center; gap: var(--stack-sm); margin-top: var(--stack-md); color: var(--accent); font-weight: 600; text-decoration: none; }
.site-footer { display: flex; justify-content: space-between; flex-wrap: wrap; gap: var(--stack-sm) var(--stack-md); padding-block: var(--stack-md) var(--stack-lg); color: var(--ink-soft); font-size: 13px; }
.skip-link { position: absolute; left: -10000px; top: 12px; padding: 12px 18px; color: var(--ink); background: var(--bg-elev); z-index: 100; }
.skip-link:focus { left: 22px; }
@media (max-width: 640px) {
  .directory { grid-template-columns: 1fr; gap: 0; }
  .intro { margin-bottom: var(--stack-lg); }
  .site-header { gap: 14px; }
  .brand { font-size: 18px; }
  .theme-toggle { font-size: 12px; }
}
@media (max-width: 420px) {
  .site-header { grid-template-columns: minmax(0, 1fr) auto; row-gap: 20px; }
  .euler { grid-column: 1 / -1; grid-row: 2; }
  .theme-toggle { grid-column: 2; grid-row: 1; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; scroll-behavior: auto !important; }
}