.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(20px);
  background: linear-gradient(to bottom, rgba(2, 6, 23, 0.98), rgba(2, 6, 23, 0.92));
  border-bottom: 1px solid var(--color-border-subtle);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-3);
  padding-bottom: var(--space-3);
  gap: var(--space-4);
}
.brand-wrapper {
  display: flex;
  align-items: center;
}
.brand-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
}
.brand-mark {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 1.25rem;
  border: 1px solid rgba(148, 163, 184, 0.5);
  background: radial-gradient(circle at 30% 0%, rgba(56, 189, 248, 0.3), rgba(15, 23, 42, 0.98));
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-text-primary);
}
.brand-text {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}
.brand-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}
.brand-subtitle {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--color-text-muted);
}
.primary-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}
.nav-item {
  position: relative;
}
.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-pill);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  transition: color var(--transition-base), background-color var(--transition-base), box-shadow var(--transition-base);
}
.nav-link::after {
  content: "";
  position: absolute;
  inset-inline: 0.6rem;
  bottom: 0.25rem;
  height: 2px;
  border-radius: 999px;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.8), transparent);
  opacity: 0;
  transform: scaleX(0.7);
  transform-origin: center;
  transition: opacity var(--transition-base), transform var(--transition-base);
}
.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-text-primary);
  background-color: rgba(15, 23, 42, 0.9);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.9);
}
.nav-link:hover::after,
.nav-link:focus-visible::after {
  opacity: 1;
  transform: scaleX(1);
}
.nav-cta-wrapper {
  margin-left: var(--space-2);
}
.header-cta {
  padding-inline: 1.5rem;
}
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.7);
  background: radial-gradient(circle at 10% 0%, rgba(56, 189, 248, 0.18), rgba(15, 23, 42, 0.98));
  cursor: pointer;
  gap: 0.3rem;
}
.nav-toggle-bar {
  width: 1.2rem;
  height: 2px;
  border-radius: 999px;
  background-color: var(--color-neutral-200);
  transition: transform var(--transition-base), opacity var(--transition-base), background-color var(--transition-base);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:first-child {
  transform: translateY(4px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:last-child {
  transform: translateY(-4px) rotate(-45deg);
}
@media (max-width: 900px) {
  .header-inner {
    padding-top: var(--space-2);
    padding-bottom: var(--space-2);
  }
  .primary-nav {
    position: fixed;
    inset-inline: 0;
    top: 3.5rem;
    background: radial-gradient(circle at top, rgba(15, 23, 42, 0.98), rgba(2, 6, 23, 1));
    border-bottom: 1px solid var(--color-border-subtle);
    flex-direction: column;
    align-items: stretch;
    padding: var(--space-4) var(--space-4) var(--space-6);
    gap: var(--space-4);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition-base), opacity var(--transition-base);
  }
  .primary-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-list {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-1);
  }
  .nav-link {
    width: 100%;
    justify-content: space-between;
    padding-inline: var(--space-3);
  }
  .nav-cta-wrapper {
    margin-left: 0;
  }
  .header-cta {
    width: 100%;
    justify-content: center;
  }
  .nav-toggle {
    display: inline-flex;
  }
}
@media (max-width: 520px) {
  .brand-subtitle {
    display: none;
  }
}
.header-inner a:focus-visible,
.nav-toggle:focus-visible {
  box-shadow: var(--shadow-focus-ring);
}

/* §10 hamburger X — 3 bars */
.nav-toggle {
  flex-direction: column;
  gap: 5px;
  width: 44px;
  height: 44px;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}