水波效果

.download-app {
  position: fixed;
  bottom: 0;
  left: 0;
  z-index: 20;
  color: #fff;
  font-size: 24px;

  overflow: hidden;
  width: 100%;
  height: 84px;
  background: url("../../../../assets/images/base/wave_bg.png") repeat-x;
  background-size: cover;
  -webkit-animation: download 3s cubic-bezier(0.32, 0.5, 0.8, 0.62) infinite;
  animation: download 3s cubic-bezier(0.32, 0.5, 0.8, 0.62) infinite;
  -webkit-transition: all 0.3s;
  transition: all 0.3s;

  .wave_ball {
    z-index: 10;
  }

  .image {
    position: absolute;
    top: -10px;
    width: 200px;
    height: 100%;
    background: url(" wave.png") no-repeat
      50% / contain;
  } 
}

@-webkit-keyframes download {
  0% {
    background-position-x: -750px;
  }

  to {
    background-position-x: 750px;
  }
}

@keyframes download {
  0% {
    background-position-x: -750px;
  }

  to {
    background-position-x: 750px;
  }
}