[Edi]

I very much prefer the black background that CoE3 uses. The background inside the infoboxes is actually dark gray, unless opacity set to 0, in which case the background is black.

I rather intensely disliked the Dominions 3 red background, it made all graphics seem indistinct and blurry. The Blue GUI mod was a little better, but not a whole lot.

Some of the sprites in CoE3 are the exact same ones as in Dom3, but they look so much better on the black background that I thought they were entirely new sprites (Sirrush, Watcher).

You can even see it when you turn opacity up to max and the background is dark gray instead of black, the visual quality immediately becomes worse.