How to Custom CSS target slide titles

Hey I was wondering if anyone could help me target this in a custom css edit, 

"<div class="image-slide-title" id="yui_3_17_2_1_1578678346736_3907">Words</div>"

More Specifically, I'm trying to change the font for 'image slide title' to something other than the default body font on the page. 

I haven't coded in a long time and i'm a bit out of my element. Can anyone help me make a css injection?

Thanks !

.image-slide-title {
   font-family: futura-pt !important;
}