/* ================================
   HEADER
================================ */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background-color: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color 0.3s, border-color 0.3s, transform 0.3s;
}

.header.is-scrolled,
body[data-solid-header] .header {
  background-color: var(--color-blue);
  border-bottom-color: var(--border-on-dark-soft);
}

/* Hidden while scrolling down (revealed on scroll up / at top) */
.header.header--hidden:not(:focus-within) {
  transform: translateY(-100%);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  width: 100%;
  padding-inline: var(--space-lg);
}

/* center the main nav between logo and CTA */
.header__nav {
  flex: 1;
  justify-content: center;
}

.header__logo {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
}

.header__logo img {
  height: var(--header-logo-height);
  width: auto;
}

.header__nav {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.header__nav a {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-white);
  transition: color 0.15s;
}

.header__nav a:hover {
  color: var(--color-yellow);
}

.header__nav .nav-dropdown {
  position: relative;
}

.nav-dropdown__heading {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

/* Invisible bridge over the gap so the menu stays open while the cursor
   travels from the toggle down to the menu items. */
.header__nav .nav-dropdown::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 12px;
}

.header__nav .nav-dropdown__toggle {
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  background: none;
  border: none;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-white);
  font-family: var(--font-sans);
  transition: color 0.15s;
}

.header__nav .nav-dropdown__toggle:hover {
  color: var(--color-yellow);
}

.header__nav .nav-dropdown__arrow {
  padding: var(--space-xs);
}

.nav-dropdown__menu {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: var(--color-white);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-md);
  min-width: 220px;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.nav-dropdown.is-open .nav-dropdown__menu {
  display: block;
}

.nav-dropdown__menu a {
  display: block;
  padding: 10px 16px;
  font-size: var(--text-sm);
  color: var(--color-blue);
  transition: background 0.15s;
}

.nav-dropdown__menu a:hover {
  background-color: var(--color-hover);
}

.nav-dropdown__menu a + a,
.mobile-nav__group a + a {
  margin-top: var(--space-xs);
}

.header a:focus-visible,
.header button:focus-visible,
.header summary:focus-visible {
  outline: 2px solid var(--color-yellow);
  outline-offset: 2px;
}

.site-fallback {
  position: absolute;
  top: calc(var(--header-height) + var(--space-xs));
  left: var(--space-lg);
  z-index: 101;
  width: max-content;
  max-width: calc(100% - var(--space-lg) * 2);
  background-color: var(--color-blue);
  color: var(--color-white);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  font-size: var(--text-sm);
}

.site-fallback > summary {
  padding: var(--space-sm);
  cursor: pointer;
}

.site-fallback > nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  max-height: calc(100vh - var(--space-xl) - var(--space-lg));
  max-height: calc(100dvh - var(--space-xl) - var(--space-lg));
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--space-xs) var(--space-sm) var(--space-sm);
}

.site-fallback:not([open]) > nav { display: none; }

.site-fallback a {
  padding-block: var(--space-xs);
  overflow-wrap: anywhere;
}

.site-fallback summary:focus-visible,
.site-fallback a:focus-visible {
  outline: 2px solid var(--color-yellow);
  outline-offset: -2px;
}

.site-fallback[hidden],
html[data-site-initializing] .site-fallback { display: none; }

.nav-dropdown__menu a:focus-visible {
  outline-offset: -4px;
  background-color: var(--color-hover);
}

.header__cta {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.header__support {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-white);
  transition: color 0.15s;
}

.header__support:hover {
  color: var(--color-yellow);
}

/* Compact membership action, balanced against the logo wordmark */
.btn.header__join {
  justify-content: center;
  flex-shrink: 0;
  min-height: calc(var(--space-md) + var(--space-sm));
  border-radius: var(--radius-pill);
  padding: var(--space-xs) calc(var(--space-md) - var(--space-xs));
  font-size: var(--header-join-font-size);
  font-weight: 600;
  line-height: 1;
  background-color: var(--color-yellow);
  color: var(--color-blue);
}

.btn.header__join:focus-visible {
  outline-color: var(--color-white);
}

/* Mobile hamburger */
.header__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}

.header__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-white);
  transition: all 0.2s;
}

/* ===== Mobile nav — full-screen overlay ===== */
.mobile-nav {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 200;
  background-color: var(--color-blue);
  color: var(--color-white);
  flex-direction: column;
  overflow-y: auto;
  overscroll-behavior: contain;
}

.mobile-nav.is-open { display: flex; }

/* top bar: logo + close */
.mobile-nav__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding-inline: var(--space-md);
  flex-shrink: 0;
}

.mobile-nav__close {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-white);
  font-size: 30px;
  line-height: 1;
  padding: 4px 8px;
  transition: color 0.15s;
}

.mobile-nav__close:hover { color: var(--color-yellow); }

.mobile-nav__body {
  display: flex;
  flex-direction: column;
  padding: var(--space-sm) var(--space-md) var(--space-xl);
}

/* top-level items + collapsible group headers share the same look */
.mobile-nav__link,
.mobile-nav__group > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-md);
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--color-white);
  transition: color 0.15s;
}

.mobile-nav__link:hover,
.mobile-nav__group > summary:hover { color: var(--color-yellow); }

.mobile-nav__group > summary {
  cursor: pointer;
  list-style: none;
}

.mobile-nav__group > summary::-webkit-details-marker { display: none; }

.mobile-nav__group > summary::after {
  content: '+';
  font-size: var(--text-2xl);
  font-weight: 300;
  color: var(--color-yellow);
}

.mobile-nav__group[open] > summary::after { content: '−'; }

/* when open, drop the summary's big bottom padding so the first
   sub-link sits close under the group header */
.mobile-nav__group[open] > summary { padding-bottom: var(--space-xs); }

/* generated sub-links (projects / departments) — stacked, indented, muted */
.mobile-nav__group a {
  display: block;
  padding-block: var(--space-xs);
  padding-left: var(--space-sm);
  font-size: var(--text-lg);
  font-weight: 500;
  color: rgba(255, 255, 255, 0.7);
  transition: color 0.15s;
}

.mobile-nav__group a:hover { color: var(--color-white); }
.mobile-nav__group a:last-child { padding-bottom: var(--space-sm); }

/* Join Us: same row style as the other top-level links, but yellow */
.mobile-nav__link--join { color: var(--color-yellow); }
.mobile-nav__link--join:hover { color: var(--color-white); }

/* ================================
   FOOTER
================================ */
.footer {
  background-color: var(--color-dark-grey);
  color: var(--color-white);
  padding-top: var(--space-lg);
}

/* centered bottom block */
.footer__bottom {
  border-top: 1px solid var(--border-on-dark-soft);
  padding-inline: var(--space-lg);
  padding-block: var(--space-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
}

.footer__social {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-md);
}

.footer__social a {
  color: rgba(255,255,255,0.7);
  transition: color 0.15s;
}

.footer__social a:hover {
  color: var(--color-white);
}

.footer__events {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-sm);
}

.footer__social svg { display: block; }

.footer__legal {
  display: flex;
  gap: var(--space-md);
  font-size: var(--text-sm);
  color: rgba(255,255,255,0.7);
}

.footer__legal a:hover {
  color: var(--color-white);
}

.footer__copy {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.5);
  text-align: center;
}

/* ================================
   GRID
================================ */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-md);
}

.grid-2-1 {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: var(--space-lg);
  align-items: center;
}

.grid-1-2 {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: var(--space-lg);
  align-items: center;
}

@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 900px) {
  .header__nav { display: none; }
  .header__cta { display: none; }
  .header__support { display: none; }
  .header__hamburger { display: flex; flex-shrink: 0; }
  .header__inner { gap: var(--space-xs); padding-inline: var(--space-md); }
  .site-fallback {
    left: var(--space-md);
    max-width: calc(100% - var(--space-md) * 2);
  }
  .footer__bottom,
  .footer__copy { padding-inline: var(--space-md); }

  .grid-2,
  .grid-3,
  .grid-4,
  .grid-2-1,
  .grid-1-2 {
    grid-template-columns: 1fr;
    gap: var(--space-sm);
  }

  .footer__legal {
    flex-wrap: wrap;
    justify-content: center;
  }
}