How do I override the font in a Portfolio Overlay Grid?

I have added very basic code under Design>Custom CSS to add a font and apply it to h1, h2, h3, and h4 headers.  The fonts are changed everywhere except one section in my home page, which uses a Portfolio Grid Overlay.  There are three photos across with titles in each one which disappear when you mouse over them.  I can find where to edit the words in these titles, but the font is not changed at all by the added CSS code.  There is an h4 header below this block that has been changed by the CSS code.  I was thinking of inserting a code block but the section with the Portfolio Grid Overlay does not have an insertion point.  Any advice?  Are these titles possibly something other than the standard h1, h2, etc...?