Brief pause between opening Brief add-on tab and loading custom CSS

[eberhardweber]

I recently started using a custom CSS for the Brief interface and there is a visible period of maybe 1 second in loading the Brief add-on tab where it utilizes the default styling before loading the actual custom stylesheet.

I figured I would make a bug report given that it is a real though minor annoyance given that I'm using a so-called " dark" theme, which leads to the Brief screen flashing a blinding bright white before loading the dark colour values.

Perhaps the stylesheet loading could be speeded up or prioritized?

[tanriol]

I'm not exactly sure where to store this information for faster retrieval, but this is definitely a bug.