.model-viewer {
  width: 100%;
  aspect-ratio: 4 / 3;
  background: #fff;
  overflow: hidden;
  position: relative;
  cursor: pointer;
  margin: 1em auto;
}
.model-viewer canvas { display: block; }
.model-viewer.expanded {
  position: fixed;
  inset: 24px;
  width: auto;
  height: auto;
  aspect-ratio: auto;
  margin: 0;
  z-index: 10000;
  cursor: default;
  box-shadow: 0 8px 32px rgba( 0, 0, 0, 0.4 );
}
.model-viewer-backdrop {
  position: fixed;
  inset: 0;
  background: rgba( 0, 0, 0, 0.7 );
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
}
.model-viewer-backdrop.visible {
  opacity: 1;
  pointer-events: auto;
}