header {
  border-radius: var(--radius-xl);
  background: rgba(10, 10, 15, 0.7);
  backdrop-filter: blur(var(--blur-amount));
  -webkit-backdrop-filter: blur(var(--blur-amount-safari));
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: auto;
  margin: 1rem 1.5rem;
  border: 1px solid var(--glass-border);
  z-index: var(--z-fixed);
  box-shadow: var(--shadow-lg);
  transition: all var(--transition-base);
  animation: fadeInDown 0.5s ease;
}

header:hover {
  box-shadow: var(--shadow-xl), var(--shadow-glow);
  border-color: var(--color-primary);
}

header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
  padding: 0 2rem;
  position: relative;
}

header nav .logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  transition: all var(--transition-base);
}

header nav .logo:hover {
  transform: scale(1.05);
}

header nav .logo img {
  height: 3.6rem;
  filter: drop-shadow(0 0 10px var(--color-primary));
  transition: all var(--transition-base);
  animation: pulse 3s ease infinite;
}

@keyframes pulse {
  0%, 100% {
    filter: drop-shadow(0 0 10px var(--color-primary));
  }
  50% {
    filter: drop-shadow(0 0 20px var(--color-secondary));
  }
}

header nav h1 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 700;
  letter-spacing: 1px;
}

header nav ul {
  display: flex;
  list-style: none;
  gap: var(--spacing-sm);
}

header nav ul a {
  text-decoration: none;
  position: relative;
}

header nav ul a li {
  padding: var(--spacing-xs) var(--spacing-md);
  color: var(--text-main);
  font-weight: 500;
  position: relative;
  transition: all var(--transition-base);
  border-radius: var(--radius-md);
}

header nav ul a li::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  transform: translateX(-50%);
  transition: width var(--transition-base);
}

header nav ul a li:hover::before {
  width: 80%;
}

header nav ul a li:hover {
  color: var(--color-secondary);
  background: var(--glass-card);
  transform: translateY(-2px);
}

header nav ul a li::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--gradient-primary);
  opacity: 0;
  border-radius: var(--radius-md);
  transition: opacity var(--transition-base);
  z-index: -1;
}

header nav ul a li:hover::after {
  opacity: 0.1;
}

.mobile-menu-toggle {
  display: none;
  font-size: 1.5rem;
  cursor: pointer;
  padding: var(--spacing-xs);
  color: var(--color-secondary);
  transition: all var(--transition-base);
}

.mobile-menu-toggle:hover {
  transform: rotate(90deg);
  color: var(--color-primary);
}

/* Scroll Effect */
header.scrolled {
  margin: 0.5rem 1rem;
  box-shadow: var(--shadow-xl);
  background: rgba(10, 10, 15, 0.9);
}

/* Responsive */
@media (max-width: 768px) {
  header nav {
    padding: 0 1rem;
  }

  header nav h1 {
    font-size: 1.25rem;
  }

  header nav ul {
    position: fixed;
    top: 5.5rem;
    right: 1.5rem;
    flex-direction: column;
    background: rgba(10, 10, 15, 0.95);
    backdrop-filter: blur(var(--blur-amount));
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    gap: var(--spacing-xs);
    transform: translateX(120%);
    transition: transform var(--transition-base);
    box-shadow: var(--shadow-xl);
  }

  header nav ul.active {
    transform: translateX(0);
  }

  header nav ul a li {
    width: 200px;
    text-align: center;
  }

  .mobile-menu-toggle {
    display: block;
  }
}

@media (max-width: 480px) {
  header {
    margin: 0.5rem;
  }

  header nav .logo img {
    height: 2.8rem;
  }

  header nav h1 {
    font-size: 1rem;
  }
}