Reduce color flash

[MichaelCurrin]

When using a background like Unicron even fixed colors, the screen shows as green/red and then the custom color appears.

I am already using the custom color on cover as per docs. But set something in CSS to override the image behind that to be white/black/grey gradient as more neutral. Or even set that color there.

Use local CSS where possible to avoid fetching a file and then loading it. Or maybe the flicker is just JS execution.