/* Header Layout */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(10, 10, 10, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-4) 0;
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}

/* Brand/Logo */
.site-brand {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.site-logo {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  text-shadow: 0 0 20px var(--color-accent-glow);
  transition: text-shadow var(--duration-fast) var(--ease-in-out);
}

.site-brand:hover .site-logo {
  text-shadow: 0 0 30px var(--color-accent-glow), 0 0 50px var(--color-primary-glow);
  color: var(--color-accent-hover);
}

/* Primary Navigation */
.primary-nav {
  display: flex;
  align-items: center;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-link {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  padding: var(--space-2) 0;
  position: relative;
  transition: color var(--duration-fast) var(--ease-in-out);
  text-decoration: none;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  transition: width var(--duration-normal) var(--ease-in-out);
  box-shadow: 0 0 10px var(--color-primary-glow);
}

.nav-link:hover,
.nav-link:focus {
  color: var(--color-text-primary);
  text-shadow: 0 0 10px rgba(250, 250, 250, 0.3);
}

.nav-link:hover::after,
.nav-link:focus::after {
  width: 100%;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  gap: 6px;
  padding: 0;
  transition: border-color var(--duration-fast) var(--ease-in-out);
}

.mobile-menu-toggle:hover {
  border-color: var(--color-accent);
}

.mobile-menu-toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.hamburger-bar {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: all var(--duration-normal) var(--ease-in-out);
  border-radius: 2px;
}

/* Mobile Menu Open State */
.mobile-menu-toggle[aria-expanded="true"] .hamburger-bar:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-bar:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-bar:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* Responsive Styles */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
    order: 2;
  }

  .primary-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-4);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--duration-normal) var(--ease-in-out);
    pointer-events: none;
  }

  .primary-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    box-shadow: var(--shadow-lg);
  }

  .nav-list {
    flex-direction: column;
    gap: var(--space-4);
    width: 100%;
  }

  .nav-link {
    display: block;
    width: 100%;
    padding: var(--space-3) 0;
    font-size: var(--text-base);
  }

  .nav-link::after {
    bottom: var(--space-1);
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  .primary-nav,
  .nav-link::after,
  .hamburger-bar {
    transition: none;
  }
}