向前滚动的进度条

直接上图

思路

在一个固定宽高的div中，内部有一个高度100%，宽度为0的div，如“signloadbackview”，这个div背景中填充一个螺旋进度条小块，如：

代码

<div class="signloadbackview signloadbackviewanim signloadbackviewwidth">div>

.signloadbackview{
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
    max-width: 5.92rem;
    height: 0.32rem;
    position: absolute;
    left: 0.05rem;
    top: 0.06rem;
    border-radius: 0.44rem;
    background: url(data:image/png;base64,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);
}
.signloadbackviewwidth{
    width: 5.92rem;
}
.signloadbackviewanim{
    -webkit-animation: loadrotate 2s linear 1;
            -moz-animation: loadrotate 2s linear 1;
              -o-animation: loadrotate 2s linear 1;
         animation: loadrotate 2s linear 1;
}
@-webkit-keyframes loadrotate {
  0% {
      width: 0%;
       background-position: 0.4rem 0;
  }
  50% {
      width: 50%;
       background-position: 0.2rem 0;
  }
  100% {
      width: 100%;
     background-position: 0rem 0;
  }
}