igualaSombras=function(){
	var h;
	var hH;
	var cd;
	var ci;
	h = document.getElementById("columna_centro");
	hH = h.offsetHeight;
	cd = document.getElementById("columna_md");
	ci = document.getElementById("columna_mi");
	cd.style.height = hH + 'px';
	ci.style.height = hH + 'px';
}