.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--color-bg-dark);
  border-bottom: 1px solid var(--color-border-light);
  z-index: var(--z-sticky);
  transition: background var(--transition-base);
}

.header--scrolled {
  background: rgba(11, 17, 32, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom-color: rgba(255, 255, 255, 0.04);
}

.header__container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text-inverse);
  text-decoration: none;
  transition: opacity var(--transition-fast);
  letter-spacing: -0.02em;
}

.header__logo:hover {
  opacity: 0.8;
}

.header__logo-icon {
  display: flex;
  align-items: center;
}

.header__nav {
  display: flex;
}

.header__menu {
  display: flex;
  gap: var(--space-1);
}

.header__link {
  display: block;
  padding: var(--space-2) var(--space-4);
  color: rgba(255, 255, 255, 0.5);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast), background var(--transition-fast);
}

.header__link:hover {
  color: var(--color-text-inverse);
  background: rgba(255, 255, 255, 0.05);
}

.header__link.active {
  color: var(--color-accent);
}

.header__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-1);
}

.header__toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text-inverse);
  border-radius: 2px;
  transition: transform var(--transition-base), opacity var(--transition-fast);
}

.header__toggle[aria-expanded="true"] span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.header__toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.header__toggle[aria-expanded="true"] span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

@media (max-width: 768px) {
  .header__nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--color-bg-dark);
    border-bottom: 1px solid var(--color-border-light);
    padding: var(--space-4);
    display: none;
  }

  .header__nav.is-open {
    display: block;
  }

  .header__menu {
    flex-direction: column;
    gap: var(--space-1);
  }

  .header__toggle {
    display: flex;
  }
}