fix: no styling applied to h1-headings in markdown (closes #1668)

[mschmidm]

This fixes #1668 about h1-markdown-headings not being styled.

Bug Explanation

The reason why h1 elements weren't styled but h2 elements were is that h2 got its styling from nextcloud/server/core/css/apps.scss:60-68 which does not contain h1 styles, as the comment explains:

/* BASE STYLING ------------------------------------------------------------ */
// no h1 allowed since h1 = logo
h2 {
    font-weight: bold;
    font-size: 20px;
    margin-bottom: 12px;
    line-height: 30px;
    color: var(--color-text-light);
}

As a fix, I added a custom h1 styling to markdownOutput.scss. I just used the styling from the form title.

Results

Now this:

Becomes this:

[Chartman123]

Hi @mschmidm,

thank you for your contribution. 👍🏻 I will do a quick review.

[Chartman123]

@mschmidm DCO doesn't pass as your signed-of-by doesn't match your configured values in your git commit... (see https://github.com/nextcloud/forms/pull/1743/checks?check_run_id=17542451176)

This should be fixed on your end so that this check will also pass (see dcoapp/app#114 (comment))

Other than that, the PR looks fine :)

[mschmidm]

Ah okay, the DCO should be fixed now. Thank you! :)

[susnux]

Ok, but should we sanitize the markdown output to move h1 and h2 to h3 and h4 (and others as well)?
I mean h1 and h2 will break the page layout.

[Chartman123]

I mean h1 and h2 will break the page layout.

@susnux in which case? Could you please post a screenshot?

[mschmidm]

Ok, but should we sanitize the markdown output to move h1 and h2 to h3 and h4 (and others as well)? I mean h1 and h2 will break the page layout.

Seems reasonable, but I think this is different issue.

@Chartman123 I think susnux means that it is currently possible (and likely) two have an incorrect heading order. The form title is a h2. If the user now adds a h1 in the description, there is a wrong order, which is discouraged due to accessibility.
This is the source code of my previous example: A h1 after a h2:

[susnux]

Lets first merge this and then fix the heading orders for descriptions later on

[Chartman123]

Yes because in the end we couldn't make sure that a description of a question that is semantically below a description of a form mustn't contain a header with a smaller number... And what to do with a h6 header then... It's a difficult topic