Transparent icons set background color

[kathykeating]

Font Awesome icons are often transparent (e.g. arrow-circle-right) and when we use this library to lay the marker onto the map the icons are difficult to see because of this transparency.

Ideally there would be a way with this to add a background color behind the transparency so that the font awesome marker comes out solid. For example, with arrow-circle-right, I would want the circle to be green and the arrow to be white, not transparent.

I've tried CSS, but something about how these are generated is prohibiting CSS as well.