Cooldown widget, circle instead of square?

[Xubera]

I am working on this addon that uses circular buttons, and I want to incorporate cooldowns in that.

In earlier projects, I just used an over lay picture that covered up the corners... however this time around, i got a design that I like, and the overlay border is too thin, letting the cooldown box protrude...

do I just need to accept that fact and either have my cooldown stick out, or be too small, or just make my overlay border thicker?