/* Layout and navigation (owner: UI/UX). Mobile first; text only, no images or icons. */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

.skip-link { position: absolute; left: -999px; top: 0; padding: var(--space-sm) var(--space-md); background: var(--color-bg); color: var(--color-accent); border: 2px solid var(--color-accent); z-index: 10; }
.skip-link:focus { left: var(--space-md); top: var(--space-md); }

.site-header { border-bottom: var(--rule-width) solid var(--color-accent); background: var(--color-surface); }
.site-title { margin: 0 0 var(--space-sm); font-family: var(--font-heading); font-size: var(--text-xl); font-weight: bold; color: var(--color-accent); line-height: var(--leading-tight); }
.site-header ul { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: var(--space-xs) var(--space-sm); }
.site-header nav a { display: block; padding: var(--space-sm) 0.75rem; min-height: 44px; text-decoration: none; border-bottom: var(--rule-width) solid transparent; }
.site-header nav a:hover { border-bottom-color: var(--color-accent); }
.site-header nav a[aria-current="page"] { font-weight: bold; color: var(--color-accent-strong); border-bottom-color: var(--color-highlight); }
.site-header nav a:focus-visible { outline: 3px solid var(--color-focus); outline-offset: 2px; }

main { max-width: var(--measure); margin: 0 auto; padding: var(--space-md); overflow-wrap: break-word; font-size: var(--text-base); line-height: var(--leading-body); }
main h1 { font-size: var(--text-2xl); line-height: var(--leading-tight); }
main h2 { margin-top: var(--space-lg); font-size: var(--text-xl); line-height: var(--leading-tight); }
main :focus-visible { outline: 3px solid var(--color-focus); outline-offset: 2px; }
main table { width: 100%; border-collapse: collapse; }
main th, main td { padding: var(--space-sm); border: 1px solid var(--color-rule); text-align: left; vertical-align: top; }

.site-footer { max-width: var(--measure); margin: var(--space-lg) auto 0; border-top: 1px solid var(--color-rule); font-size: var(--text-sm); color: var(--color-muted); }

@media (min-width: 40rem) {
  .site-header { display: flex; align-items: center; justify-content: space-between; gap: var(--space-md); }
  .site-title { margin: 0; }
  main h1 { font-size: var(--text-3xl); }
}

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