message: fix(content-block): remove bottom margin from last child
diff: @mixin content-block-media {
  .#{$prefix}--content-block-media {
  @include themed-items;
  +
  + .#{$prefix}--content-group:last-child {
  + margin-bottom: 0;
  + }
  }
  .#{$prefix}--content-block-media--g100 {
  