@layer compositions {
  .imposter {
    position: var(--positioning, absolute);
    inset-block-start: 50%;
    inset-inline-start: 50%;
    transform: translate(-50%, -50%);
  }

  .imposter.contain {
    --margin: 0px;
    overflow: auto;
    max-inline-size: calc(100% - (var(--margin) * 2));
    max-block-size: calc(100% - (var(--margin) * 2));
  }
}