/* ========================================
   HEADER STYLES
   ======================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-neutral-200);
  box-shadow: var(--shadow-sm);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
}

.site-logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  color: var(--color-text);
  transition: opacity var(--transition-fast);
}

.site-logo:hover {
  opacity: 0.8;
  color: var(--color-text);
}

.site-logo__text {
  font-family: var(--font-family-heading);
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.main-nav {
  display: flex;
  align-items: center;
}

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

.nav-link {
  display: block;
  padding: var(--space-2) 0;
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--color-text);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.nav-link:hover,
.nav-link:focus {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary-light);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.header-icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  color: var(--color-text);
  background-color: transparent;
  border: 1px solid var(--color-neutral-300);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-fast);
}

.header-icon-btn:hover {
  background-color: var(--color-neutral-100);
  color: var(--color-primary);
  border-color: var(--color-primary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  background: transparent;
  border: 1px solid var(--color-neutral-300);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.mobile-menu-toggle:hover {
  background-color: var(--color-neutral-100);
}

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

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 1.25rem;
  height: 2px;
  background-color: var(--color-text);
  transition: transform var(--transition-base), background-color var(--transition-base);
}

.hamburger {
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}

.hamburger::before {
  top: -6px;
}

.hamburger::after {
  top: 6px;
}

/* Mobile Menu Open State */
.mobile-menu-toggle[aria-expanded="true"] .hamburger {
  background-color: transparent;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger::before {
  transform: translateY(6px) rotate(45deg);
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger::after {
  transform: translateY(-6px) rotate(-45deg);
}

/* Responsive */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
    order: 1;
  }
  
  .header-actions {
    order: 2;
  }
  
  .site-logo {
    order: 0;
  }
  
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    padding: var(--space-4) var(--space-5);
    background-color: var(--color-surface);
    border-top: 1px solid var(--color-neutral-200);
    border-bottom: 1px solid var(--color-neutral-200);
    box-shadow: var(--shadow-lg);
  }
  
  .nav-menu.is-open {
    display: flex;
  }
  
  .nav-item {
    width: 100%;
    border-bottom: 1px solid var(--color-neutral-100);
  }
  
  .nav-item:last-child {
    border-bottom: none;
  }
  
  .nav-link {
    padding: var(--space-4) 0;
    border-bottom: none;
  }
  
  .nav-link:hover {
    border-bottom: none;
    padding-left: var(--space-2);
  }
}