How can I use CSS to realize text formatting in edit mode?

[Marco]

We use CSS in custom html to adjust the font family and heading sizes, among other things. This works well in view mode, but unfortunately the stylesheets do not work in edit mode because the WYSIWYG editor is obviously loaded as an iFrame.

Do you know a way to insert styles anyway?
Especially the different sized headings in edit and view mode regularly confuse our authors...

Thanks, 
Marco

[Vronik]

Take a look at these articles, I don't know if they can help you

https://confluence.atlassian.com/doc/styling-fonts-in-confluence-174751968.html

https://confluence.atlassian.com/doc/styling-confluence-with-css-166528400.html

[Marco]

Hi @Vronik thanks for your feedback.
Unfortunatly this doesn't change the style in Edit Mode so the users have different UX in view and edit mode (tested in Confluence 8.5 LTS).