@keyframes fadein {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 0.5;
    }
}

._dash-loading-callback {
    font-family: sans-serif;
    padding-top: 50px;
    color: rgb(90, 90, 90);

    /* The banner */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    text-align: center;
    cursor: progress;

    opacity: 0;
    background-color: rgb(250, 250, 250);
    /* Delay animation by 1s to prevent flashing
       and smoothly transition the animation over 0.5s
     */

    -moz-animation: fadein 0.5s ease-in 1s forwards; /* Firefox */
    -webkit-animation: fadein 0.5s ease-in 1s forwards; /* Safari and Chrome */
    -o-animation: fadein 0.5s ease-in 1s forwards; /* Opera */
    animation: fadein 0.5s ease-in 1s forwards;

}