body {
  background-color: #333;
}

.loading {
    position: relative;
    display: inline-block;
}

.loading::before{
    content: "";
    position: absolute;
    width: 100px;
    height: 100px;
    background-color: #1c5ba2;
    border-radius: 100%;
    z-index: 5;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    -webkit-animation: slide-top 0.5s ease-out infinite alternate ;
        animation: slide-top 0.5s ease-out infinite alternate ;
 }

 #c {
     position: relative;
     background-color: black;
 }

/* ----------------------------------------------
 * Generated by Animista on 2019-9-17 14:35:13
 * Licensed under FreeBSD License.
 * See http://animista.net/license for more info.
 * w: http://animista.net, t: @cssanimista
 * ---------------------------------------------- */

/**
 * ----------------------------------------
 * animation slide-top
 * ----------------------------------------
 */
 @-webkit-keyframes slide-top {
    0% {
      -webkit-transform: translate(-50%, 50%);
              transform: translate(-50%, 50%);
    }
    100% {
      -webkit-transform: translate(-50%, -150%);
              transform: translate(-50%, -150%);
    }
  }
  @keyframes slide-top {
    0% {
      -webkit-transform: translate(-50%, 50%);
              transform: translate(-50%, 50%);
    }
    100% {
      -webkit-transform: translate(-50%, -150%);
              transform: translate(-50%, -150%);
    }
  }