.loader {    
    /*position: fixed;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    z-index: 9999;
    background: url('/Imagen/imag.gif') 50% 50% no-repeat rgb(249,249,249);
    opacity: .8;  
    position:center; 

    text-align:center; 
   justify-content: center;
   align-items: center;*/

            position: absolute;
        top: 50%;
        left: 50%;
        width: 640px;
        height: 120px;
        margin-left: -320px;
        margin-top: -60px;
        font-size: 24px;
        color: gray;
        opacity: 0.4;

}

/*.loader {
  border: 16px solid #f3f3f3; 
  border-top: 16px solid #3498db; 
  border-radius: 50%;
  width: 120px;
  height: 120px;
  animation: spin 2s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}*/