function mudaCor()
{
    var total = 4;
	var num = Math.floor(Math.random()*total) + 1;
    
    if(document.getElementById('site').className=='cor'+num){
    	
    	if(num>=total)
    		num=1;
    	else
    		num=num+1;
    		
    }
    
    document.getElementById('site').className='cor'+num;
    document.body.className='IBg'+num;

    //alert('cor'+num);  

}