/* Header layout and branding */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(18px);
  background: linear-gradient(to bottom, rgba(5,6,8,0.94), rgba(5,6,8,0.86));
  border-bottom: 1px solid rgba(37, 41, 56, 0.9);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-3);
  gap: var(--space-4);
}

.site-header__brand {
  display: flex;
  align-items: center;
}

.site-header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
}

.site-header__logo-cube {
  width: 28px;
  height: 28px;
  border-radius: 6px;
  background: radial-gradient(circle at 20% 0%, rgba(54,227,255,0.85), transparent 65%),
              linear-gradient(135deg, #36e3ff, #3fffb2);
  box-shadow: var(--shadow-neon);
  position: relative;
}

.site-header__logo-cube::after {
  content: "";
  position: absolute;
  inset: 4px;
  border-radius: inherit;
  border: 1px solid rgba(5,6,8,0.65);
  box-shadow: inset 0 0 0 1px rgba(5,6,8,0.75);
}

.site-header__logo-text {
  font-family: var(--font-display);
  font-size: 1.05rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

/* Navigation */
.site-header__nav {
  display: flex;
}

.site-header__nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  list-style: none;
}

.site-header__nav-link {
  font-family: var(--font-display);
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  padding-block: 0.25rem;
}

.site-header__nav-link::after {
  height: 2px;
  bottom: -0.45rem;
}

.site-header__nav-link:hover,
.site-header__nav-link:focus-visible {
  color: var(--color-text);
}

/* Mobile toggle (hamburger) */
.site-header__toggle {
  display: none;
  width: 42px;
  height: 42px;
  padding: 0;
  border-radius: 999px;
  border: 1px solid var(--color-border-subtle);
  background: radial-gradient(circle at 0% 0%, rgba(54,227,255,0.26), transparent 55%),
              rgba(8, 10, 18, 0.98);
}

.site-header__toggle-bar {
  width: 18px;
  height: 2px;
  border-radius: 999px;
  background-color: var(--color-text);
  transition: transform var(--transition-base), opacity var(--transition-base), background-color var(--transition-base);
}

/* Toggle animation when open */
.site-header--menu-open .site-header__toggle-bar:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.site-header--menu-open .site-header__toggle-bar:nth-child(2) {
  opacity: 0;
}

.site-header--menu-open .site-header__toggle-bar:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* Mobile navigation behaviour */
@media (max-width: 768px) {
  .site-header__toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
  }

  .site-header__nav {
    position: fixed;
    inset-inline: 0;
    top: 64px;
    background: linear-gradient(to bottom, rgba(5,6,8,0.98), rgba(5,6,8,0.96));
    border-top: 1px solid rgba(37, 41, 56, 0.9);
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), transform var(--transition-base), visibility var(--transition-base);
  }

  ul.site-header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-4) var(--space-4) var(--space-6);
    gap: var(--space-3);
  }

  .site-header__nav-link {
    font-size: 0.85rem;
  }

  .site-header--menu-open .site-header__nav {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }
}

/* Desktop tweaks */
@media (min-width: 769px) {
  .site-header__nav {
    position: static;
    opacity: 1 !important;
    visibility: visible !important;
    transform: none !important;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .site-header__nav,
  .site-header__toggle-bar {
    transition: none;
  }
}