Transparency color for pop-ups

[Ekmek]

Ok I was trying to fix my leaderhead stuff so it doesn't have empty space and instead make it transparent so you can see the background map instead (although you cant touch it )

I tried 0,0,0 black and hthe 248,0,248 pink and it didn't work. Anyone know how to do this? this was attempted on dipwizard.ldl