/* css/nav.css — header, mega menu, mobile nav, sticky mobile CTA */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--color-border-subtle);
}
/* The translucent blur lives on a decorative ::before rather than directly on .site-header,
   because backdrop-filter on an ancestor establishes a new containing block for any
   position:fixed descendant (like the mobile nav panel below) — that silently shrank the
   full-screen mobile menu down to the header's own height, letting page content show through. */
.site-header::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: rgba(10, 13, 20, 0.86);
  backdrop-filter: blur(10px);
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  padding-block: 1rem;
  min-height: var(--header-height);
}

.logo {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--color-text-primary);
  flex-shrink: 0;
}
.logo-dot { color: var(--color-sapphire-400); }

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 0.5rem;
}
.nav-toggle-bar,
.nav-toggle-bar::before,
.nav-toggle-bar::after {
  content: '';
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text-primary);
  transition: transform 200ms ease-out, opacity 200ms ease-out;
}
.nav-toggle-bar::before { transform: translateY(-6px); }
.nav-toggle-bar::after { transform: translateY(4px); }
body.nav-open .nav-toggle-bar { background: transparent; }
body.nav-open .nav-toggle-bar::before { transform: translateY(0) rotate(45deg); background: var(--color-text-primary); }
body.nav-open .nav-toggle-bar::after { transform: translateY(-2px) rotate(-45deg); background: var(--color-text-primary); }

.nav-collapse {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
  position: fixed;
  inset: var(--header-height) 0 0 0;
  background: var(--color-bg-primary);
  padding: var(--space-8) 1.5rem;
  overflow-y: auto;
  transform: translateY(-8px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 200ms ease-out, transform 200ms ease-out;
}
body.nav-open .nav-collapse {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}

.mega-menu {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.mega-menu > li > details > summary {
  list-style: none;
  cursor: pointer;
  padding: 0.85rem 0.25rem;
  font-weight: 600;
  border-bottom: 1px solid var(--color-border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.mega-menu > li > details > summary::-webkit-details-marker { display: none; }
.mega-menu > li > details > summary::after {
  content: '+';
  color: var(--color-sapphire-400);
  font-weight: 400;
}
.mega-menu > li > details[open] > summary::after { content: '\2212'; }

.mega-panel {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-4) 0.25rem var(--space-6);
}
.mega-panel a {
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
}
.mega-panel a:hover,
.mega-panel a:focus-visible { background: var(--color-bg-surface); color: var(--color-text-primary); }

.nav-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  margin-top: auto;
  padding-top: var(--space-6);
}

.sticky-mobile-cta {
  position: fixed;
  left: 1rem; right: 1rem; bottom: 1rem;
  z-index: 90;
  opacity: 0;
  transform: translateY(16px);
  pointer-events: none;
  transition: opacity 200ms ease-out, transform 200ms ease-out;
}
.sticky-mobile-cta.is-visible { opacity: 1; transform: none; pointer-events: auto; }
.sticky-mobile-cta .cta { width: 100%; }

.back-to-top {
  position: fixed;
  right: 1rem;
  bottom: 6rem;
  z-index: 91;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-full);
  border: none;
  background: var(--color-sapphire-500);
  color: #fff;
  box-shadow: var(--shadow-card);
  cursor: pointer;
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity 200ms ease-out, transform 200ms ease-out, background 150ms ease;
}
.back-to-top.is-visible { opacity: 1; transform: none; pointer-events: auto; }
.back-to-top:hover { background: var(--color-sapphire-400); }
.back-to-top svg { width: 1.15rem; height: 1.15rem; }

/* Desktop layout */
@media (min-width: 1024px) {
  .nav-toggle { display: none; }

  .nav-collapse {
    position: static;
    flex-direction: row;
    align-items: center;
    background: none;
    padding: 0;
    opacity: 1;
    transform: none;
    pointer-events: auto;
    inset: auto;
    overflow: visible;
  }

  .mega-menu {
    flex-direction: row;
    gap: var(--space-8);
    position: relative;
  }
  .mega-menu > li > details > summary {
    border-bottom: none;
    padding: 0.5rem 0;
  }
  .mega-menu > li > details[open] > summary::after,
  .mega-menu > li > details > summary::after { content: ''; }
  .mega-panel {
    position: absolute;
    top: calc(100% + 0.75rem);
    left: 0;
    min-width: 16rem;
    background: var(--color-bg-surface);
    border: 1px solid var(--color-border-subtle);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-card);
    padding: var(--space-4);
  }

  .nav-actions {
    flex-direction: row;
    align-items: center;
    margin-top: 0;
    padding-top: 0;
  }

  .sticky-mobile-cta { display: none; }
  .back-to-top { bottom: 1.5rem; }
}