change background to semitransparent 

http://3.bp.blogspot.com/-QeqMlLq41z8/Uv-T3PsvRLI/AAAAAAAAAsM/z0YvVP-TBlQ/s1600/Screenshot_2014-02-15-21-48-41.png
Merge pull request #1 from rush25/patch-1

change background to semitransparent