.site-header {
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-gray-200);
  position: sticky;
  top: 0;
  z-index: 1000;
}
.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--space-20);
}
.site-logo {
  font-family: var(--font-serif);
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-text);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.primary-nav {
  display: flex;
}
.nav-list {
  display: flex;
  list-style: none;
  gap: var(--space-8);
}
.nav-link {
  font-family: var(--font-sans);
  font-size: var(--font-size-sm);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-gray-800);
  position: relative;
  padding: var(--space-2) 0;
}
.nav-link::after {
  content: '';
  position: absolute;
  width: 0;
  height: 1px;
  bottom: 0;
  left: 0;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}
.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-text);
}
.nav-link:hover::after,
.nav-link:focus-visible::after {
  width: 100%;
}
.mobile-menu-toggle {
  display: none;
}
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    width: 28px;
    height: 24px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
  }
  .hamburger-line {
    width: 100%;
    height: 2px;
    background-color: var(--color-text);
    transition: all var(--transition-fast);
  }
  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
  }
  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
  }
  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
  }
  .primary-nav {
    position: fixed;
    top: 0;
    right: -100%;
    width: 85%;
    max-width: 400px;
    height: 100vh;
    background-color: var(--color-bg);
    box-shadow: -5px 0 15px rgba(0,0,0,0.05);
    transition: right var(--transition-base);
    flex-direction: column;
    padding: var(--space-24) var(--space-8);
    visibility: hidden;
    overflow-y: auto;
  }
  .primary-nav.is-open {
    right: 0;
    visibility: visible;
  }
  .nav-list {
    flex-direction: column;
    gap: var(--space-6);
  }
  .nav-link {
    font-size: var(--font-size-lg);
    display: block;
  }
}