message: fix border radius on background
diff: top: 0;
  right: 0;
  left: 0;
  - border-radius: var(--boxel-border-radius) var(--boxel-border-radius) 0 0;
  + border-radius: var(--boxel-border-radius);
  overflow: hidden;
  z-index: 0;
  height: 14.375rem;
  