This seems to solve the problem indeed.

But I have a product description on some pages, like http://www.worldofpixels.be/product/canvas/ for example, with the css provided everything is deleted.

How can I help this?

Normally, only in this category the product description should be visible, on all the other future ones there won’t even be a description:

http://www.worldofpixels.be/product-category/prijzen-prijslijst/

Thank you !