/* Skip Link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  z-index: 100;
  transition: top var(--transition-fast);
  font-weight: 500;
}

.skip-link:focus {
  top: 0;
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Header Layout */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  font-weight: 700;
  font-size: var(--text-xl);
  color: var(--color-text);
  letter-spacing: -0.025em;
  flex-shrink: 0;
}

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

.logo__text {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  width: 2.5rem;
  height: 2.5rem;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text);
  background: transparent;
  border: 1px solid var(--color-border);
}

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

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

.hamburger {
  display: block;
  width: 1.25rem;
  height: 2px;
  background-color: currentColor;
  position: relative;
  transition: background-color var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: currentColor;
  transition: transform var(--transition-fast);
}

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

.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);
}

/* 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-list a {
  display: block;
  padding: var(--space-2) 0;
  color: var(--color-text-secondary);
  font-weight: 500;
  font-size: var(--text-sm);
  position: relative;
  transition: color var(--transition-fast);
}

.nav-list a:hover,
.nav-list a:focus {
  color: var(--color-primary);
}

.nav-list a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-primary);
  transform: scaleX(0);
  transition: transform var(--transition-fast);
}

.nav-list a:hover::after,
.nav-list a:focus::after {
  transform: scaleX(1);
}

/* Mobile Styles */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
  }
  
  .primary-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    border-top: 1px solid var(--color-border-light);
    padding: var(--space-4);
    transform: translateY(-10px);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-lg);
    flex-direction: column;
    align-items: stretch;
  }
  
  .primary-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  
  .nav-list {
    flex-direction: column;
    gap: var(--space-1);
    width: 100%;
  }
  
  .nav-list li {
    width: 100%;
  }
  
  .nav-list a {
    padding: var(--space-3);
    border-radius: var(--radius-md);
    width: 100%;
    color: var(--color-text);
  }
  
  .nav-list a:hover,
  .nav-list a:focus {
    background-color: var(--color-surface);
    color: var(--color-primary);
  }
  
  .nav-list a::after {
    display: none;
  }
}