phpbb3 problem?!?!?

ok i have been playing with phpbb3 since phpbb2 is a little stuffed lol, i have a test forum and added a chatbox to see what it looked likeand it didnt turn out so well, the bottom bit of the chatbox isnt really there. Can any of you help me to fix this problem as the phpbb3 skin i found is a nice one and wouldnt mind using it.
Here is a pic of the chatbox, sorry if its a bit too big.(by the way it isnt the full chatbox i just wanted you guys to see the prob)