.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(252, 251, 249, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-gray-200);
  padding-block: var(--space-4);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-brand {
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--color-text);
  letter-spacing: 0.02em;
  text-transform: capitalize;
}

.primary-nav .nav-list {
  display: flex;
  gap: var(--space-6);
  list-style: none;
}

.primary-nav a {
  font-size: var(--text-sm);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text);
  position: relative;
  padding-block: var(--space-1);
}

.primary-nav a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--color-primary);
  transition: width var(--transition-normal);
}

.primary-nav a:hover::after,
.primary-nav a:focus-visible::after {
  width: 100%;
}

.mobile-menu-toggle {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  z-index: 101;
}

.mobile-menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  margin-block: 5px;
  transition: transform var(--transition-normal), opacity var(--transition-normal);
}

@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: block;
  }
  
  .primary-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background-color: var(--color-bg);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
  }

  .primary-nav.is-open {
    opacity: 1;
    visibility: visible;
  }

  .primary-nav .nav-list {
    flex-direction: column;
    align-items: center;
    gap: var(--space-8);
  }

  .primary-nav a {
    font-size: var(--text-xl);
  }

  .mobile-menu-toggle[aria-expanded="true"] span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }
  .mobile-menu-toggle[aria-expanded="true"] span:nth-child(2) {
    opacity: 0;
  }
  .mobile-menu-toggle[aria-expanded="true"] span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }
}