function changeActive(key) {

	var sections = document.getElementsByClassName("seccion");
	
	for (var i = 0; i < sections.length; i ++) {
	
		sections[i].setAttribute("class", "seccion");

		sections[i].setAttribute("className", "seccion");
	
	}
	sections[(key)].setAttribute("class", "seccion activa");

	sections[(key)].setAttribute("className", "seccion activa");
}
	

function categoriaActiva(key){    
	if (key!=null){changeActive(key)}
}