Hi Tobias
We removed this feature because you can break the entire GUI if you don’t know what you do. We kept the mechanism of custom CSS but you have to copy to the right place in the course resoruce folder as a system administrator.
The way to go for most cases is to implement various course layouts as part of your theme. Normal authors can then choose form the list of predefined course layouts, e.g. one or each institution on your installation. This is much better because you can be sure that users don’t break the layout. If you create such course layouts, just add a folder “courselayouts” to your system theme and in there create a folder for each course theme you want to have. For each course theme provide a main.css and an iframe.css file and a preview.png so users will know how your course theme looks like. The main.css is added to the main window while the iframe.css is added to your content that is running in an iframe.
If you still want to do you own per-course thing, there is a hidden feature. Create a folder “courseCSS” in the course folder and add a file main.css and iframe.css. Both files are needed.
Note that with OpenOLAT 10 you will have to redo your themes as most CSS classes are not valid anymore and you will have many new elements in a course that could possibly be styled.
Cheers
Florian