message: use ActionCardContainer::Section for layout customization card
diff: --background-swatch-height: 1.5rem;
  }
  -.layout-customization__body {
  - padding: 0 var(--boxel-sp-lg);
  -}
  -
  -.layout-customization__body-header {
  - display: flex;
  - align-items: center;
  - padding: var(--boxel-sp-xl) 0;
  - font-size: 1.125rem;
  - font-weight: 600;
  -}
  -
  .layout-customization__disclaimer {
  margin-top: var(--boxel-sp-xxl);
  - margin-bottom: var(--boxel-sp-lg);
  font: var(--boxel-font-xs);
  color: var(--boxel-purple-400);
  }
  