Font colours are bad

[Craigjw]

Describe the bug

There is no way to change the font colour. The UI is mostly dark/black and the pop-up prompt boxes have black text, which can't be seen because, black on black.

An example of this is when creating a new dataset, a pop-up prompt appears to input the dataset name, showing black text on a black background.

[Tsubashi]

I've found that this flips and shows up correctly when my system is in dark mode. It seems to apply to any un-styled text that inherits the color parameter from body