Custom HUD progress bar

Hi, i don’t know if this is the right sectionfor this topic, but i was thinking so. Aniway, my problem is this: i’m making a simply hud with health and shield bar, and i made a custome image for them, with diagonal vertical borders, and they look nice. When the bar is not filled, the end is no more diagonal. How to correct it?
P.S. forgive my bad english and thanks.