Dear Flanakin

Thanks... that you'll answer to my question...
I don't use special css... I think there is no css mistakes... but I use some javascript...
The page that I want to see is:
Click here
And in normal view, you can see this page in firefox.
I've set the heigth of the Iframe to 800px... But it seems that the height in firefox is not 800px. 

Dear Flanakin

Thanks for your suggestion. Now I remember that I've something like this before. Firefox need a <div></div> tag around some items... I've also looked at the code...

<div id="dnn_ctr500_ModuleContent"><span id="dnn_ctr500_IFrame_lblIFrame"><iframe frameborder="no" src="http://www.stabiton.net/Portals/0/html/VanuitGent.htm" height="800px" width="100%" title="@ Givabo :: Reisroute vanuit Kortrijk - Oostende - Gent" name="@ Givabo :: Reisroute vanuit Kortrijk - Oostende - Gent" scrolling="auto">Uw browser ondersteunt geen frames</iframe></span></div>

It seems that my firefox is configured that he don't accept frames...

That's also the reason why I don't think it is in the my skin... because the Iframe runs in a container. I'm gone change my container and try to specify the height of the td-tag... style="height:100%". I don't think that a div-tag arround the content will help... Because there is allready a div-tag...  Have you a special reason why the Iframe runs in a span-tag?... And why is the height of the Iframe not 800px like I've set? (normally it must be 800px... and by me it's about 50px with the content of the htm file... )

I let you know if I found something... I'll appreciate if you've other suggestions...