Is there any way to increase the size of the plus and minus icons?

[justinbyoung]

I am trying to make my thermostat a bit more tablet friendly by making the icons larger and easier to press.

Using CSS I am able to increase the test size of the temp font, but I would love to be able to increase the + and - icon sizes as well. I imagine there is some way to use card-mod to do this, but if someone has some guidence it would be appreciated.