/* Header Layout */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background-color: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  transition: background-color var(--transition-base);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

/* Brand */
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--color-text-primary);
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  letter-spacing: -0.02em;
  transition: color var(--transition-fast);
}

.brand-logo {
  color: var(--color-primary);
  font-size: var(--text-3xl);
}

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

/* Navigation */
.main-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-display);
  font-size: var(--text-base);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-2) 0;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

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

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

/* Mobile Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 44px;
  height: 44px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  z-index: 1001;
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2px;
  background-color: currentColor;
  transition: transform var(--transition-base), opacity var(--transition-base);
  transform-origin: center;
}

.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);
}

/* Responsive */
@media (max-width: 1024px) {
  .mobile-menu-toggle {
    display: flex;
  }
  
  .nav-list {
    position: fixed;
    top: 80px;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-bg-primary);
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-6);
    gap: var(--space-2);
    transform: translateX(100%);
    transition: transform var(--transition-base);
    overflow-y: auto;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
  }
  
  .nav-list.is-open {
    transform: translateX(0);
  }
  
  .nav-item {
    width: 100%;
  }
  
  .nav-link {
    display: block;
    font-size: var(--text-xl);
    padding: var(--space-3) 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  }
  
  .header-actions {
    display: none;
  }
}

@media (max-width: 768px) {
  .header-container {
    height: 64px;
  }
  
  .brand-text {
    font-size: var(--text-xl);
  }
  
  .nav-list {
    top: 64px;
  }
}