Simple animation while waiting for an answer

bounce.css

#followingBalls {
  position: relative;
  height: 20px;
  width: 256px;
  margin: 50px auto;
  display: block;
}

#followingBalls .ball {
  background-color: #333;
  position: absolute;
  top: 0;
  left: 0;
  width: 20px;
  height: 20px;
  border-radius: 10px;
  background-clip: padding-box;
  animation-name: bounce;
  animation-duration: 1.9s;
  animation-iteration-count: infinite;
}

#followingBalls #ball-1 {
  animation-delay: 0s;
}

#followingBalls #ball-2 {
  animation-delay: 0.19s;
}

#followingBalls #ball-3 {
  animation-delay: 0.38s;
}

#followingBalls #ball-4 {
  animation-delay: 0.57s;
}


@keyframes bounce {
    0% {
        left: 0;
        background-color: #333
    }

    50% {
        left: 236px;
        background-color: #eee
    }

    100% {
        left: 0;
        background-color: #333
    }
}

bounce.html

<div id="followingBalls">
            <div id="ball-1" class="ball"></div>
            <div id="ball-2" class="ball"></div>
            <div id="ball-3" class="ball"></div>
            <div id="ball-4" class="ball"></div>
        </div>

See it here: https://jsfiddle.net/0aupm3xf/