Shrinking logo in fullwith menu

Hi Team!
Im wandering if is posible to shrink the logo in the fullwith menu (the fixed element)
I tryed to add a class to the menu when is fixed to the top (in avia.js line 1383):

					if(scrolled + modifier > top_pos)
					{
						if(!fixed)
						{
							this.css({top: modifier - bordermod, position: 'fixed'}); fixed = true;
							this.addClass('fix');
						}
					}

But that code add the class to the menu no manner if is fixed to the top or not.

Any other solution?
Thanks a lot team!