.site-header {
  position: sticky;
  z-index: var(--z-navbar);
  top: 0;

  width: 100%;

  border-bottom: 1px solid transparent;

  background: rgba(5, 5, 5, 0.72);

  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);

  transition:
    border-color var(--transition-normal),
    background var(--transition-normal);
}

.site-header.scrolled {
  border-bottom-color: var(--border-subtle);

  background: rgba(5, 5, 5, 0.9);
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;

  height: var(--navbar-height);
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;

  flex-shrink: 0;

  color: var(--text-primary);

  font-size: 17px;
  font-weight: var(--weight-bold);

  letter-spacing: -0.035em;
}

.nav-brand-mark {
  position: relative;

  display: grid;
  place-items: center;

  width: 22px;
  height: 22px;

  border: 1px solid var(--border-strong);
  border-radius: 7px;

  background: var(--surface-3);
}

.nav-brand-mark::before {
  width: 6px;
  height: 6px;

  border-radius: 2px;

  background: var(--text-primary);

  content: "";
}

.nav-center {
  position: absolute;

  left: 50%;

  display: flex;
  align-items: center;

  gap: 4px;

  transform: translateX(-50%);
}

.nav-link {
  position: relative;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  min-height: 38px;

  padding: 0 12px;

  border-radius: var(--radius-sm);

  color: var(--text-muted);

  font-size: 13px;
  font-weight: var(--weight-medium);

  transition:
    color var(--transition-fast),
    background var(--transition-fast);
}

.nav-link:hover {
  color: var(--text-primary);

  background: var(--surface-2);
}

.nav-link.active {
  color: var(--text-primary);
}

.nav-link.active::after {
  position: absolute;

  right: 12px;
  bottom: 4px;
  left: 12px;

  height: 1px;

  border-radius: var(--radius-full);

  background: var(--text-primary);

  content: "";
}

.nav-actions {
  display: flex;
  align-items: center;

  gap: 8px;
}

.nav-login {
  display: inline-flex;
  align-items: center;
  justify-content: center;

  min-height: 38px;

  padding-inline: 13px;

  border-radius: var(--radius-sm);

  color: var(--text-secondary);

  font-size: 13px;
  font-weight: var(--weight-medium);

  transition:
    color var(--transition-fast),
    background var(--transition-fast);
}

.nav-login:hover {
  color: var(--text-primary);

  background: var(--surface-2);
}

.nav-invite {
  display: inline-flex;
  align-items: center;
  justify-content: center;

  min-height: 38px;

  padding-inline: 15px;

  border: 1px solid #ffffff;
  border-radius: var(--radius-sm);

  background: #ffffff;
  color: #050505;

  font-size: 13px;
  font-weight: var(--weight-semibold);

  transition:
    opacity var(--transition-fast),
    transform var(--transition-fast);
}

.nav-invite:hover {
  opacity: 0.88;

  transform: translateY(-1px);
}

.mobile-menu-button {
  display: none;

  position: relative;

  width: 40px;
  height: 40px;

  border: 1px solid var(--border-default);
  border-radius: var(--radius-sm);

  background: var(--surface-2);
}

.mobile-menu-button span {
  position: absolute;

  left: 11px;

  width: 16px;
  height: 1px;

  background: var(--text-primary);

  transition:
    transform var(--transition-normal),
    top var(--transition-normal),
    opacity var(--transition-normal);
}

.mobile-menu-button span:nth-child(1) {
  top: 14px;
}

.mobile-menu-button span:nth-child(2) {
  top: 19px;
}

.mobile-menu-button span:nth-child(3) {
  top: 24px;
}

.mobile-menu-button.open span:nth-child(1) {
  top: 19px;

  transform: rotate(45deg);
}

.mobile-menu-button.open span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-button.open span:nth-child(3) {
  top: 19px;

  transform: rotate(-45deg);
}

.mobile-navigation {
  display: none;

  overflow: hidden;

  max-height: 0;

  border-top: 1px solid transparent;

  opacity: 0;

  transition:
    max-height var(--transition-slow),
    opacity var(--transition-normal),
    border-color var(--transition-normal);
}

.mobile-navigation.open {
  max-height: 500px;

  border-top-color: var(--border-subtle);

  opacity: 1;
}

.mobile-navigation-inner {
  display: flex;
  flex-direction: column;

  gap: 5px;

  padding-block:
    var(--space-4)
    var(--space-6);
}

.mobile-nav-link {
  display: flex;
  align-items: center;
  justify-content: space-between;

  min-height: 48px;

  padding-inline: var(--space-4);

  border-radius: var(--radius-sm);

  color: var(--text-secondary);

  font-size: var(--font-sm);
  font-weight: var(--weight-medium);

  transition:
    color var(--transition-fast),
    background var(--transition-fast);
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
  color: var(--text-primary);

  background: var(--surface-2);
}

.mobile-nav-link::after {
  color: var(--text-subtle);

  content: "→";

  font-family: var(--font-mono);
}

.mobile-nav-actions {
  display: grid;

  grid-template-columns: 1fr 1fr;

  gap: var(--space-2);

  margin-top: var(--space-3);

  padding-top: var(--space-4);

  border-top: 1px solid var(--border-subtle);
}

.mobile-nav-action {
  display: flex;
  align-items: center;
  justify-content: center;

  min-height: 44px;

  border: 1px solid var(--border-default);
  border-radius: var(--radius-sm);

  background: var(--surface-2);

  color: var(--text-secondary);

  font-size: var(--font-sm);
  font-weight: var(--weight-medium);
}

.mobile-nav-action.primary {
  border-color: var(--accent);

  background: var(--accent);
  color: var(--accent-foreground);

  font-weight: var(--weight-semibold);
}

@media (max-width: 860px) {
  .nav-center,
  .nav-actions {
    display: none;
  }

  .mobile-menu-button,
  .mobile-navigation {
    display: block;
  }
}

@media (max-width: 480px) {
  .nav-brand {
    font-size: 16px;
  }

  .nav-brand-mark {
    width: 20px;
    height: 20px;
  }

  .mobile-nav-actions {
    grid-template-columns: 1fr;
  }
}