![tabs_before](https://f.cloud.github.com/assets/1704508/494045/52b55918-bb82-11e2-9576-cc9105a0ddc1.png) ![tabs_after](https://f.cloud.github.com/assets/1704508/494046/589facca-bb82-11e2-82a2-bb265ba81ab7.png)

The background should contains opacity 0.75, not solid black background. You can use !important to override the styles in building blocks.