/* ============================================
   Navigation & Header Styles
   ============================================ */

.site-header {
  position: sticky;
  top: 0;
  background-color: var(--color-background);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  z-index: 1000;
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--spacing-sm);
  padding-bottom: var(--spacing-sm);
  min-height: 64px;
}

/* Brand */
.navbar-brand {
  flex-shrink: 0;
}

.brand-link {
  font-size: var(--text-xl);
  font-weight: var(--font-bold);
  color: var(--color-text);
  transition: color var(--transition-fast);
}

.brand-link:hover {
  color: var(--color-primary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 40px;
  height: 40px;
  padding: 8px;
  background-color: transparent;
  border: none;
  cursor: pointer;
  z-index: 1001;
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition-base);
}

.hamburger-line:not(:last-child) {
  margin-bottom: 5px;
}

/* Mobile menu toggle animation */
.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
  transform: translateY(7px) 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(-7px) rotate(-45deg);
}

/* Navigation Menu */
.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: block;
  padding: 0.5rem 0.75rem;
  color: var(--color-text-light);
  font-weight: var(--font-medium);
  font-size: var(--text-base);
  transition: color var(--transition-fast);
  position: relative;
}

.nav-link:hover {
  color: var(--color-primary);
}

/* Active link indicator */
.nav-link.active {
  color: var(--color-primary);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0.75rem;
  right: 0.75rem;
  height: 2px;
  background-color: var(--color-primary);
  border-radius: 2px;
}

/* Focus styles */
.nav-link:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 4px;
  border-radius: var(--radius-sm);
}

/* ============================================
   Mobile Responsive Navigation
   ============================================ */

@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-sm) 0;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height var(--transition-base), opacity var(--transition-base);
  }

  .nav-menu.active {
    max-height: 400px;
    opacity: 1;
  }

  .nav-item {
    width: 100%;
  }

  .nav-link {
    display: block;
    padding: var(--spacing-sm) var(--spacing-md);
    width: 100%;
  }

  .nav-link.active::after {
    left: var(--spacing-md);
    right: auto;
    width: 4px;
    height: 100%;
    top: 0;
    bottom: 0;
  }
}

/* ============================================
   Tablet and Desktop
   ============================================ */

@media (min-width: 769px) {
  .navbar {
    padding-top: var(--spacing-md);
    padding-bottom: var(--spacing-md);
  }

  .nav-menu {
    gap: var(--spacing-lg);
  }
}