#entrada{
	position: absolute;
	top: 50%;
	left: 50%;
	margin-top: -260px;
	margin-left: -400px;
	background-color: Black;  
}
	#principal{
	position: absolute;
	top: 50%;
	left: 50%;
	margin-top: -300px;
	margin-left: -497px;
	background-color: Black;  
}