Yes I already tried that, but I now want to stretch it using css, like we do on our own website. And there are other elements I need to change, like the top border of the right column elements, it's the original light blue. Do I have to dig in the standard stylesheet and put the overrides in the custom css form field?
We have applied some styles from your website. Check your customCSS field and your community. If you need more help give us some screen with description what you want to apply and we will help you.
You can prepare your CSS using http://www.csspivot.com
or StyleBot Chrome plugin https://chrome.google.com/extensions/detail/oiaejidbmkiecgbjeifoejpgmdaleoha
then we just put in your CSS on top of our own and it will have the highest priority.
Also soon be available to apply custom css from admin interface.