Fixed styling error, preventing iframe border and window scrolling

When running twd on Ubuntu (GNOME, un-tested on others), the scrollbars cause the window to overflow and waste space.

The iframe also has a nasty border.

*Before*
![twd-before](https://cloud.githubusercontent.com/assets/7271686/4215335/77f23e16-38cd-11e4-8b9a-d9a26fea64fb.jpg)

*After*
![twd-after](https://cloud.githubusercontent.com/assets/7271686/4215338/7ed8dd66-38cd-11e4-805c-f0f23c893da9.jpg)