Font size error

I don't know if this is a bug, I probably just pressed a wrong button.

I was on the chatbox yesterday, I was typing something quickly into the message box and my finger hit two keys (one of them was the space bar if it helps), This seemed to change the default font size of the entire chatbox (and now that I check, the whole forum) to something very small.
I managed to get by, by increasing the minimum font size option in my browser (firefox) to something larger however this messes up all of the other websites.

I don't know what I've done or how to fix it.
If anyone knows how to fix it then please help.

EDIT:
I just cleared my cache and that fixed it. Sorry about that.