Blocks with code over more than one line look strange

Hi There!

I'm trying do adjust an existing theme to my needs. Right now i've got the problem that code fields over more than one line look pretty strange. Here's a example

http://img498.imageshack.us/img498/8263/snap22ke.png

or here's the url of that page

http://www.christoph-langner.de/drupal/?q=node/13

Drupal draws a new block for each line. The node content looks like this (of course with pointy brackets)

[code]
this is a test line1
this is a test line1
[/code]

I would hope that the result would look like this. Especially the with of the block should go over the whole page.

this is a test line1
this is a test line2

So here's the simple question. How can i do this?

Thanks
Christoph