Agenda Export: some improvements needed

[MSoeb]

Current behavior
The agenda export needs some improvements.

Wanted behavior

• Headings: Reduce the size of all headings slightly.
• Indentation: Subheadings should be indented.
• If subheadings contain text, this should appear below the heading. No further indentation is necessary.
• Spacing between logo (top left) and text: The spacing here needs to be increased. The text is too close to the logo.

Additional context
Maybe some more improvements are needed. We have to figured out, what seems to be missing and what looks good during testing.

Please contact me for further information about the topic. I have a comparison of old and new export in our Nextcloud. So we can see, which improvements are needed.

[bspekker]

The issue #6003 is related to problems with the export and might be solved together.