/* Header Styles */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(17, 21, 31, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-gray-900);
  box-shadow: 0 4px 30px rgba(0, 240, 255, 0.05);
  transition: background-color var(--trans-base);
}

.header-container {
  height: 80px;
}

.brand-logo {
  text-decoration: none;
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--color-text-primary);
  text-transform: uppercase;
  display: flex;
  align-items: center;
}

.brand-accent {
  color: var(--color-primary);
  text-shadow: var(--glow-primary);
}

.main-nav .nav-list {
  list-style: none;
  gap: var(--space-6);
  margin: 0;
  padding: 0;
}

.nav-link {
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: var(--space-2) 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  box-shadow: var(--glow-primary);
  transition: width var(--trans-base);
}

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

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

.mobile-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 32px;
  height: 24px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  z-index: 1001;
}

.hamburger-line {
  width: 100%;
  height: 2px;
  background-color: var(--color-text-primary);
  border-radius: var(--radius-full);
  transition: all var(--trans-fast);
  box-shadow: 0 0 5px rgba(0, 240, 255, 0.3);
}

@media (max-width: 767px) {
  .mobile-toggle {
    display: flex;
  }
  
  .main-nav {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 400px;
    height: 100vh;
    background-color: var(--color-bg-surface);
    border-left: 1px solid var(--color-primary);
    box-shadow: -5px 0 30px rgba(0, 240, 255, 0.1);
    padding: var(--space-24) var(--space-8) var(--space-8);
    transition: right var(--trans-base);
    overflow-y: auto;
  }
  
  .main-nav.is-open {
    right: 0;
  }
  
  .main-nav .nav-list {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-6);
  }
  
  .nav-link {
    font-size: var(--text-xl);
  }
  
  .mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: translateY(11px) rotate(45deg);
    background-color: var(--color-primary);
  }
  
  .mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
  }
  
  .mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: translateY(-11px) rotate(-45deg);
    background-color: var(--color-primary);
  }
}

/* Theme Toggle Button */
.theme-toggle-btn {
  background: transparent;
  border: 1px solid var(--color-gray-700);
  color: var(--color-text-secondary);
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--trans-base);
  font-size: var(--text-lg);
  padding: 0;
}

.theme-toggle-btn:hover,
.theme-toggle-btn:focus-visible {
  color: var(--color-primary);
  border-color: var(--color-primary);
  box-shadow: var(--glow-primary);
  transform: scale(1.1);
}

body.light-theme .theme-toggle-btn {
  border-color: var(--color-gray-300);
  color: var(--color-text-secondary);
}