.gsx-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(14,16,22,0.85);
  backdrop-filter: blur(8px);
  border-bottom: var(--border-subtle);
}

.gsx-header-spacer {
  height: 84px;
}

.gsx-header-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-pad);
  height: 84px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.gsx-brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-shrink: 0;
}

.gsx-logo {
  width: 44px;
  height: 44px;
  object-fit: contain;
}

.gsx-brand-text {
  font-family: var(--font-heading);
  font-size: 1.4rem;
}

.gsx-nav {
  display: flex;
}

.gsx-nav-list {
  display: flex;
  gap: var(--space-3);
  margin: 0;
  padding: 0;
  align-items: center;
}

.gsx-nav-list li {
  margin: 0;
  padding: 0;
}

.gsx-nav a {
  color: var(--color-text-primary);
  font-size: var(--fs-sm);
  position: relative;
}

.gsx-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 1px;
  background: var(--color-accent-primary);
  transition: width 0.2s ease;
}

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

.gsx-nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
}

.gsx-nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text-primary);
}

@media (max-width: 900px) {
  .gsx-nav-toggle {
    display: flex;
    flex-direction: column;
  }

  .gsx-nav {
    position: fixed;
    top: 84px;
    right: 0;
    width: min(320px, 90vw);
    height: calc(100vh - 84px);
    background: var(--color-bg-secondary);
    border-left: var(--border-subtle);
    transform: translateX(100%);
    transition: transform 0.3s ease;
    padding: var(--space-4);
    overflow-y: auto;
  }

  .gsx-nav.open {
    transform: translateX(0);
  }

  .gsx-nav-list {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-3);
  }
}