In-Portal uses CKEditor as it's WYSIWYG editor. The CKEditor is configured in a way, that it applies CSS used on Front-End as well.
The WYISYG can be opened in these cases:
- pressing orange "Edit Content" button, when viewing website in "Content Mode"
- pressing document icon below field name for textarea controls
Unfortunately, when later approach is used the styles of website aren't initially applied, when WYSIWYG editor is shown.
This happens because CSS url doesn't immediately return CSS, but instead calls PHP script to generate it and redirects to generation result. Apparently such approach works only in 50% cases with CKEditor.
Change stylesheet URL, that is specified for CKEditor to point directly to generated CSS file instead of PHP script that generates it.