How can I modify the Icon Box icons and Headers in Enfold theme

I’d like to modify the icons in the icon box so that they match the formatting of the icons in the icon list, i.e. in a circle vs. no circle, and also to change the color of the icons and the header text. How would I call out this element in a custom css? Or is there a place to access the code for this element?
Is there a way to insert custom icons as a graphic rather than a font?

Lynda Rae
Aurora Design Studio