How do I edit collapse arrow icon?

I want to create an FAQ.

I want a question and an arrow to the far right of the box that the question is in.

I added the expand code from here but I don’t like the arrow. What css do I need to add to make the arrow look like the arrows beside the questions on the collapse-o-matic homepage? One questions asks if icecream is like gelato and there’s an arrow to the far right.

Thanks everyone!