Tabs exceeding page width

Hi,

I am trying to use the Tabs shortcode on my site, but run into a strange situation. As the added titles are more than the page width something funny happens and the text in the tabs shift to the right.

I copied the html code to a temp page http://www.newchannel.nl/test-2/ so you can see this for yourself. To my idea I put the code in correctly, but I may have missed something (although I have used the tabs before with success)

I currently use the accordion code (http://www.newchannel.nl/portfolio/appriver-e-mail-en-web-security/), but I like to the tabs better for this setup.

I hope you can help me into the right direction for this.

Best regards,
Martin