.email-branding-preview {
  width: 100%;
  box-sizing: border-box;
  border: solid 1px $border-colour;
  min-height: 200px;
  margin-bottom: $gutter
}

.email-branding-preview {
  width: 100%;
  box-sizing: border-box;
  border: solid 1px $border-colour;
  min-height: 200px;
  margin-bottom: $gutter
}

#logo-img {
  background-color: $grey-4;
  background-image: linear-gradient(45deg, $grey-3 25%, transparent 25%), linear-gradient(-45deg, $grey-3 25%, transparent 25%), linear-gradient(45deg, transparent 75%, $grey-3 75%), linear-gradient(-45deg, transparent 75%, $grey-3 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
  
  img {
    display: block;
  }
}

Put pattern behind logo images
Put pattern behind logo images

So that white on transparent images are visible.