Background fix here, buttons as in the arrow and images themselves will have to come in a later PR as they are much harder :D

the problem is with the class btn-outline-primary

Can you add a release blocker on this one please.

The easiest option is to use the same scss as for .subhead buttons

Not sure what the best way to do that with scss though so will leave it someone else to try

and for the images you can just do

.img {
filter:invert(1);
}

Can be closed as fixed elsewhere in 5.1

The white background of the image should be fixed.

I wouldnt change the images myself. They are all consistently sized, have good contrast and consistent backgrounds.