/* GNETICS Brain — site chrome (TKT-313 shared header + footer).
 * Mobile-first. Burger toggle on narrow screens; full horizontal nav ≥720px.
 * Colors/typography/focus rings come from tokens.css (TKT-312). */

/* Skip-link: visible only when focused via keyboard. */
.site-skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: var(--on-accent);
  padding: .5rem .8rem;
  border-radius: 0 0 6px 0;
  font-weight: 600;
  z-index: 1000;
}
.site-skip:focus,
.site-skip:focus-visible {
  left: 0;
}

/* Header --------------------------------------------------------------- */
.site-header {
  display: block;
  background: var(--bg);
  border-bottom: 1px solid var(--bd);
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  max-width: 1100px;
  margin: 0 auto;
  padding: .8rem 1.2rem;
}
.site-header__logo {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  color: var(--fg);
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: .01em;
}
.site-header__logo-mark {
  color: var(--accent);
  font-size: 1.25rem;
  line-height: 1;
}
.site-header__logo:hover { color: var(--accent); }

/* Burger button — shown ≤719px only. */
.site-header__burger {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 40px;
  height: 40px;
  padding: 0 9px;
  background: transparent;
  border: 1px solid var(--bd);
  border-radius: 8px;
  cursor: pointer;
}
.site-header__burger-bar {
  display: block;
  height: 2px;
  background: var(--fg);
  border-radius: 2px;
  transition: transform .18s ease, opacity .18s ease;
}
.site-header__burger[aria-expanded="true"] .site-header__burger-bar:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.site-header__burger[aria-expanded="true"] .site-header__burger-bar:nth-child(2) {
  opacity: 0;
}
.site-header__burger[aria-expanded="true"] .site-header__burger-bar:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* Nav list. Mobile: drawer hidden by default, shown when header has
 * [data-nav-open]. ≥720px: inline list, burger hidden. */
.site-header__nav {
  display: none;
}
.site-header[data-nav-open] .site-header__nav {
  display: block;
  position: absolute;
  left: 0;
  right: 0;
  top: 100%;
  background: var(--card);
  border-bottom: 1px solid var(--bd);
}
.site-header__links {
  list-style: none;
  margin: 0;
  padding: .6rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: .2rem;
}
.site-header__links a {
  display: block;
  padding: .6rem .4rem;
  color: var(--fg);
  text-decoration: none;
  font-weight: 500;
  border-radius: 6px;
}
.site-header__links a:hover { color: var(--accent); }
.site-header__links a[aria-current="page"] {
  color: var(--accent);
  background: rgba(91, 140, 255, .08);
}

@media (min-width: 720px) {
  .site-header__burger { display: none; }
  .site-header__nav,
  .site-header[data-nav-open] .site-header__nav {
    display: block;
    position: static;
    background: transparent;
    border: 0;
  }
  .site-header__links {
    flex-direction: row;
    align-items: center;
    padding: 0;
    gap: .3rem;
  }
  .site-header__links a { padding: .45rem .8rem; }
}

/* Footer --------------------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--bd);
  background: var(--bg);
  margin-top: 3rem;
}
.site-footer__inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1.4rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: .8rem;
  align-items: center;
  text-align: center;
}
.site-footer__copyright {
  margin: 0;
  color: var(--mut);
  font-size: .85rem;
}
.site-footer__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}
.site-footer__links a {
  color: var(--mut);
  text-decoration: none;
  font-size: .85rem;
}
.site-footer__links a:hover { color: var(--accent); }

@media (min-width: 720px) {
  .site-footer__inner {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}