Please change all interfaces over to dark by default, and NEVER flash the screen white while loading
This is a very simple task, please default everything to a dark theme, please don't flash any screen white, while it's loading.   I have visual problems, and the white flashing is very irritating, and the light theme is hard to focus on.   I especially do not want any area of your software to show up in a light theme, when I have the theme set to dark. 
This includes the settings panel, user pages, Atlassian administration, etc... keep everything in the same theme.
Light themes in general are hard to work with, since they are too bright and the contrast is usually terrible.  Well I'm typing this reply, I'm having a hard time focusing on the box, because my visual area is overloaded. 
I understand that other people will feel differently, so maybe the solution is to ask first, and then continue on with the theme they pick, so they can comfortably work with the software platform.