Hi,
I think it's possible,
1) TIP: you have to use :nth-child(n) property from CSS .
and even elements will have a different background color than the odd.
Right now your module uses also "inverse" class which adds schwarze Hintergrundfarbe.
.gkNspPM-NewsBlocks > figure.inverse {...} - you have to neutralize this.
2) Unfortunately, GK support does not cover this type of customization, nor CSS teaching.
But I helped a little bit.
But if you really need it regardless of conditions... send PM