public/static/spinner.css

.spinner {
    position: fixed;
    top: 40%;
    left: 50%;
    margin-left: -70px;
    width: 140px;
    text-align: center;
}

.spinner > div {
    width: 44px;
    height: 44px;
    background-color: #bdbdbd;

    border-radius: 100%;
    display: inline-block;
    -webkit-animation: bouncedelay 1.4s infinite ease-in-out;
    animation: bouncedelay 1.4s infinite ease-in-out;
    /* Prevent first frame from flickering when animation starts */
    -webkit-animation-fill-mode: both;
    animation-fill-mode: both;
}

.spinner .bounce1 {
    -webkit-animation-delay: -0.32s;
    animation-delay: -0.32s;
}

.spinner .bounce2 {
    -webkit-animation-delay: -0.16s;
    animation-delay: -0.16s;
}

@-webkit-keyframes bouncedelay {
    0%, 80%, 100% { -webkit-transform: scale(0.0) }
    40% { -webkit-transform: scale(1.0) }
}

@keyframes bouncedelay {
    0%, 80%, 100% {
        transform: scale(0.0);
        -webkit-transform: scale(0.0);
    } 40% {
          transform: scale(1.0);
          -webkit-transform: scale(1.0);
      }
}