Make a frame expand/collapse on click?

I had a thought earlier that bases a bit off the facebook chat. I have a chatbox that I want to add the bottom of pages on a website. I don't want the chatbox to constantly be available on the bottom as that looks ugly IMO. I was thinking that I would add a frame to the bottom of the pages. In its default state only the text or a picture saying "Click to expand/collapse chat" would be visible. Clicking that text/picture would resize the frame making the chatbox visible in a way that looks nice. Is this possible using just html? If not what do I need to do to add this feature?