.alerta{
  position:fixed;
  top:0;
  left:0px;
  right:0;
  z-index:1000;
  margin: 10px;
  text-align: center;
}

.alerta-navbar{
  position:fixed;
  top: 4.5rem;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 10px;
  text-align: center;
}