Hello Heiko,
Sorry if I didn't explain adequately how to do this when we corresponded by email.
You can use a div as follows:
<div style="background:#D9D9D9;">
(your regular Jutoh content)
</div>
Apply the "HTML" paragraph style to the div start and end tags (but not to your content inbetween).
I think your question about not adding a blank line refers to the after-paragraph spacing in the style you are using, so you need to edit the style and set the spacing to zero.
Regards,
Julian