This is a very simple mod that makes fluid UIs respect gases' colour.

The MM_UI_Gas material in the game does not seem to use its Tint parameter, so all gases show up as white. It is likely that CSS never noticed this issue because the only gas currently in the game is Nitrogen, which happens to be white.

This mod hooks the BPW_FluidTank widget and, if the item descriptor it is showing is a gas, replaces the "liquid material" used to draw the tank with a custom reimplementation of the MM_UI_Gas material, and sets its Tint parameter to the gas' "gas colour" property.

This mod should work with any other mods that use the BPW_FluidTank widget in their UIs, and that set their gases' "gas colour" property to a reasonable value (e.g. one that matches the colours in the icon).