body {
		background-color: #FFFFFF;
		height:100%;
		margin: 0;
		padding: 0;
		border: 0;
}


#principal{
		height: 100%;
		width: 900px; margin-left: auto; margin-right: auto;
		border: 0;
		padding: 0;
		background: #ffffff url(../images/screen.jpg) repeat;
}