Mg browser

![image](https://cloud.githubusercontent.com/assets/2095625/3411081/72951da0-fdf2-11e3-8469-f4a5a5918279.png)

![image](https://cloud.githubusercontent.com/assets/2095625/3411083/7d238bee-fdf2-11e3-932e-ee7ec2fb0d2c.png)

Why do you prefer transparentize over rgba?