All sizes, colors, etc are in CSS.
all the CSS is in the top portion of your template.
this lines control most of the forums font sizes.
QuoteBODY {font-family: Verdana, arial, helvetica, serif; font-size:12px;}
TD {font-family: Verdana, arial, helvetica, serif; color: #000000; font-size:12px;}
.windowbg {background-color: #AFC6DB; font-size: 12px; font-family: Verdana, arial, helvetica, serif; color: #000000;}
.windowbg2 {background-color: #F8F8F8; font-size: 12px; font-family: Verdana, arial, helvetica, serif; color: #000000;}
.windowbg3 {background-color: #6394BD; font-size: 12px; font-family: Verdana, arial, helvetica, serif; color: #000000;}
You will have to play the CSS to get what you want.