/**************************************************************************
**  function centrarWeb()                                                **
** Centra horizontalmente el cuerpo del site                             **
**************************************************************************/
function centrarYMostrarWeb(){
	document.getElementById('contenedor_principal').style.display = 'block';
	
	var totalWidth = document.body.offsetWidth;
	var webWidth = document.getElementById('contenedor_principal').offsetWidth;
	
	var marginLeft = (totalWidth - webWidth)/2;
	
	document.getElementById('contenedor_principal').style.marginLeft = marginLeft + 'px';
}