Formating in editing mode not the same as in view mode

Dear WPMU DEV Team,
on the first screenshot you see what the page looks like in editing mode. On the second you see how it is displayed in the browser.
I do not understand why there is such a difference.

I deleted browser cache and purged all cloudflare data and turned cloudflare to development mode.

Thank you for your help.

kind regards,
Vassi