design fixes

remove too much buttom padding
Old: 
![with-padding](https://f.cloud.github.com/assets/245432/1155711/9f40b744-1f75-11e3-89b2-6895d962870a.png)
New: 
![without-padding](https://f.cloud.github.com/assets/245432/1155712/a0d291a4-1f75-11e3-9b3d-879852e45851.png)

make line editor indicators unugly (no border radius)
![new-line-markers](https://f.cloud.github.com/assets/245432/1155721/d17f3122-1f75-11e3-8178-3fbdadf7293f.png)

That are just dirty fixes, because the styles are applied by the JS code (it would be great if this is could be moved to CSS rules only - separation of concerns, easier to fix design issues without diving into code, etc.)

Feel free to move those changes, whereever you want.

@jancborchardt Opinion?