with these changes Firefox shows padding on bottom of document

resolve #145

![pic 2013-04-13 21 08 43 ](https://f.cloud.github.com/assets/1975298/376602/1d9a8adc-a444-11e2-9c38-a8fa5c6011d8.png)


Main problem is shadows: 
Shadows on top and bottom of block demand that block shall have specific height or max-height.
But -moz-box-sizing ignores bottom padding if block has specific height or max-height.

So to keep shadows in webkit and to have bottom padding in gecko I move div.editor into div.scrollbox and tweak css.

There are few issues on small screen, I will resolve it later.