.site-header {
  position: fixed;
  inset-inline: 0;
  top: 0;
  z-index: var(--z-header);
  background: rgba(7, 9, 13, 0.55);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-normal) var(--ease-out), background var(--dur-normal) var(--ease-out);
}
.site-header[data-scrolled="true"] {
  background: rgba(7, 9, 13, 0.85);
  border-bottom-color: var(--color-border);
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  height: 72px;
}

.site-header__logo {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: 0.02em;
  margin-right: auto;
}
.logo-mark {
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--gradient-iris);
  box-shadow: 0 0 16px 2px rgba(110, 231, 255, 0.45);
}

.site-header__nav ul {
  display: flex;
  gap: var(--space-5);
}
.site-header__nav a {
  font-size: var(--fs-small);
  color: var(--color-text-dim);
  transition: color var(--dur-fast) var(--ease-out);
}
.site-header__nav a:hover { color: var(--color-text); }

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.site-header__menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
}
.site-header__menu-toggle span {
  width: 20px; height: 2px;
  background: var(--color-text);
  border-radius: 2px;
}

.mobile-nav {
  background: var(--color-bg-raised);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-5) var(--container-pad) var(--space-6);
}
.mobile-nav ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}
.mobile-nav a { font-size: var(--fs-body-lg); }

@media (max-width: 860px) {
  .site-header__nav, .site-header__actions { display: none; }
  .site-header__menu-toggle { display: inline-flex; }
}