Modify gh-pages css for firefox

Currently, Firefox supports `border-radius` and `box-shadow`.
And the another one with vender-prefix is not supported.

Before:
![ 2013-03-15 2 41 46](https://f.cloud.github.com/assets/290782/260105/785f3950-8cce-11e2-951f-11d608df7c6e.png)


After:
![ 2013-03-15 2 42 27](https://f.cloud.github.com/assets/290782/260112/9111d1b0-8cce-11e2-818b-5e37ef057370.png)