/* Header layout */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(18px);
  background-color: rgba(245, 245, 243, 0.92);
  border-bottom: 1px solid var(--color-border-subtle);
}

.site-header__topbar {
  background-color: var(--color-neutral-900);
  color: var(--color-primary-contrast);
  font-size: var(--font-size-xs);
}

.site-header__topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-16);
  padding-top: 0.4rem;
  padding-bottom: 0.4rem;
}

.site-header__topbar-text {
  color: var(--color-neutral-200);
  margin: 0;
}

.site-header__topbar-link {
  color: var(--color-neutral-50);
  text-decoration: underline;
  text-underline-offset: 0.18em;
  font-weight: 500;
}

.site-header__topbar-link:hover {
  color: var(--color-neutral-100);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-24);
  padding-top: var(--space-16);
  padding-bottom: var(--space-16);
}

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

.site-header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-12);
  padding: 0.35rem 0;
}

.site-header__logo-mark {
  width: 32px;
  height: 32px;
  border-radius: 30% 70% 60% 40% / 40% 30% 70% 60%;
  background: radial-gradient(circle at 30% 30%, #e5e7eb 0, #d1d5db 40%, #111827 100%);
  box-shadow: var(--shadow-md);
}

.site-header__logo-text {
  display: flex;
  flex-direction: column;
}

.site-header__name {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.site-header__tagline {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* Navigation */
.site-header__nav {
  flex: 1 1 auto;
}

.site-header__nav-list {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-24);
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-header__nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  padding: 0.45rem 0;
}

.site-header__nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  border-radius: var(--radius-full);
  background-color: var(--color-neutral-800);
  transition: width var(--transition-normal);
}

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

.site-header__nav-link:hover::after,
.site-header__nav-link:focus-visible::after {
  width: 100%;
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-12);
}

.site-header__cta {
  font-size: var(--font-size-xs);
  padding-inline: 1.25rem;
}

/* Mobile toggle */
.site-header__toggle {
  display: none;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 0.75rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-neutral-300);
  background-color: var(--color-surface);
  color: var(--color-text);
}

.site-header__toggle-icon {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
}

.site-header__toggle-icon span {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 999px;
  background-color: var(--color-neutral-800);
  transition: transform var(--transition-normal), opacity var(--transition-fast);
}

.site-header__toggle-label {
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.site-header__toggle[aria-expanded="true"] .site-header__toggle-icon span:first-child {
  transform: translateY(3px) rotate(45deg);
}

.site-header__toggle[aria-expanded="true"] .site-header__toggle-icon span:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

/* Responsive */
@media (max-width: 960px) {
  .site-header__inner {
    gap: var(--space-16);
  }

  .site-header__nav {
    position: absolute;
    inset-inline: 0;
    top: 100%;
    background-color: rgba(245, 245, 243, 0.98);
    border-bottom: 1px solid var(--color-border-subtle);
    transform-origin: top;
    transform: scaleY(0.8);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-normal), transform var(--transition-normal), visibility var(--transition-fast);
  }

  .site-header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-16);
    gap: var(--space-12);
  }

  .site-header__nav-link {
    width: 100%;
    padding-block: 0.6rem;
  }

  .site-header__nav--open {
    opacity: 1;
    transform: scaleY(1);
    visibility: visible;
    pointer-events: auto;
  }

  .site-header__toggle {
    display: inline-flex;
  }

  .site-header__actions {
    display: none;
  }
}

@media (max-width: 640px) {
  .site-header__topbar-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .site-header__tagline {
    display: none;
  }
}