#topo {
	position:absolute;
	left:0px;
	top:0px;
	width:777px;
	height:240px;
	z-index:1;
}
#base {
	position:absolute;
	left:0px;
	top:240px;
	width:777px;
	height:358px;
	z-index:2;
}
#base2 {
	position:absolute;
	left:0px;
	top:598px;
	width:777px;
	height:23px;
	z-index:4;
}
#cursoseventos {
	position:absolute;
	left:16px;
	top:259px;
	width:198px;
	height:296px;
	z-index:5;
}
#conteudo {	position:absolute;
	left:239px;
	top:258px;
	width:515px;
	height:303px;
	z-index:6;
}
#tudo
{
width:777px;
height:600px;
position:absolute;
left:50%;
margin-left: -388px; /* observe q coloquei a metade do width */
float:left;
}