h5向上翻页图标晃动动画，css固定h5向上翻页图标在页面上

//html结构
<div class='upImg'><div>

//css
.upImg {
  background-image: url(../images/01.png);
  position: fixed;
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
  z-index: 11;
   6.5625%;
  height: 0;
  padding-bottom: 4.063%;
  left: 50%;
  -webkit-transform: translate(-50%, 0);
  -ms-transform: translate(-50%, 0);
  transform: translate(-50%, 0);
  bottom: 42px;
  -webkit-animation: upDown_anim 2s ease-in-out infinite;
          animation: upDown_anim 2s ease-in-out infinite;
}
@-webkit-keyframes upDown_anim {
  0%,
  100% {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0);
  }
  50% {
    -webkit-transform: translate(0, 20px);
            transform: translate(0, 20px);
  }
}
@keyframes upDown_anim {
  0%,
  100% {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0);
  }
  50% {
    -webkit-transform: translate(0, 20px);
            transform: translate(0, 20px);
  }
}