Steps to reproduce: Create a Blank project (NodeJS/Docker Hosting), go to Add Framework and select a Bootswatch 5 theme (e.g.: Cyborg, which comes with a dark background). Clearly, the rendered background keeps white even after saving and refreshing the view.
@m_gabor described the same steps to reproduce the issue:
I hope a fix comes out soon (or a workaround for the time being)