How to change default margin for dynamic HTML text?

[hvbtup]

We recently changed the way we store formatted text in our DB from pseudo-HTML that we needed for Oracle Reports compatibility to normal HTML, the main difference being how line breaks are stored (OR interpreted \n as a fixed line-break, not as just whitespace).
We now use HTML p tags for paragraphs, which is canonical and also better regarding accessibility.

But two adjacent paragraphs <p>one</p><p>two</p> look like this in BIRT (PDF) output:

(empty line)
one
(empty line)
(empty line)
two
(empty line)

The empty lines are not empty lines actually, they are caused by a default margin-top and margin-bottom added for the p elements, which is probably defined as 1em.
The two empty lines in the middle are generated, because, different from browsers, if two adjacent elements have margin-bottom and margin-top, BIRT adds both values whereas Firefox takes the maximum of both values ("margin collapsing").

I could parse and modify the HTML text from the DB and eg. explicitly add style="margin-top:0.2em;margin-bottom:0.2em" (or even 0) to the p elements to create a layout without these huge gaps.

But that would mean that I need to do this in all multi-line items in all reports, which means a huge amount of work.

So the question is:

Is it possible to override the default margin values BIRT uses without modifying analyzing and modifying the HTML from the DB?

[speckyspooky]

Hi Henning, currently there is now common way to change the default.
But I have changed the P-behavior that the gap will be smaller - see #2234, there I added some example screen.

I can offer to a a userproperty at report level and/or add a systemproperty to add a common configuration.

[hvbtup]

If I understand correctly, part of the change in #2235 is that we explicitly set margin-top:0px for most HTML tags and margin-bottom:0px or (in case of a p tag) 1em if these properties are not yet set?.

Hmm, yes, this would result in an output looking like this (didn't test):

one
(empty line)
two
(empty line)

which is way better, though it wouldn't perfectly match the previous behavior when we used <br> tags.
Probably in many places we have explicitly set margin-bottom:0px anyway, and in that case (if I understand correctly), we wouldn't get the empty line at the bottom of the text, so in this case it would look good.

I think we will give #2235 it a try in our application.

Though I didn't actually test it, I'll mark your comment as answer.

Regarding a userproperty or systemproperty, I think a better solution would be if we could use a system property that points to a resource file similar to a reset.css which could override the various builtin CSS defaults. This is just a vague idea, of course BIRT doesn't fully understand CSS (it's the C which is missing in BIRT), and could be quite a lot of work.

[speckyspooky]

Yes, you are right with your interpretation.