function clean(object) {
		switch (object.value) {
			case " ":
				object.value = "";
				object.style.color = "#000000";
				break;
				
			case "Buscar":
				object.value = "";
				object.style.color = "#000000";
				break;
				
			case "usuario":
				object.value = "";
				object.style.color = "#000000";
				break;
			case "password":
				object.value = "";
				object.style.color = "#000000";
				break;
		}
}

function comproba(object) {
	if (object.value == "") {
		if (document.getElementById('usu_mail')) {
			object.value = 'usuario';				
		}else if (document.getElementById('usu_pass')) {
			object.value = 'password';	
		}
		object.style.color = "#af5000";
	}
}