@layer responsive {
  @media (max-width: 799px) {
    #panels { padding: 0; }

    .panel { width: 100vw; }

    /* Hide every panel except the last (the most recently opened). */
    .panel:not(:last-child) { display: none; }

    /* Frame overlap is a desktop affordance only. */
    .panel + .panel::before { display: none; }

    #site-header { padding-inline: var(--space-md); }
  }
}