.atualizando {
   position: absolute;
   width: 100vw;
   height: 100vh;
   top: 0;
   left: 0;
   z-index: 9999;
   background-image: url(../images/manutencao.jpg);
   background-repeat: no-repeat;
   background-size: cover;
   background-position: center;
   animation: ease-in-out 2s infinite alternate bckg-pulse;
   margin: -10px 0px;
}

   .atualizando ~ * {
      display: none;
   }

@keyframes bckg-pulse {
   from {
      transform: translateY(10px);
   }

   to {
      transform: translateY(0px);
   }
}