I recently installed some candy colour-blocked roman blinds. And I just love them! There's a bit of maths involved in working out the proportions, since I wanted at least one of the seams to line up with a rod pocket. Now they're finished, I realise that this means the pink disappears completely when the blinds are up. Maybe in future I'll try and get the narrow contrast border to land up on a fold, so that it will always be on view - but then that would change the proportions quite a bit. Hmmm, is this getting a bit technical???
In another room we added a pom pom trim along the bottom, which did mean that all three colours are on show even when the blind is pulled up: