尝试毛玻璃特效

Firefox不兼容backdrop-filter属性，但总有些需求，真的是。。。

1. Firefox用属性background-attachment、background-size可以实现毛玻璃效果

  <div class="app">
    <div class="box"></div>
  </div>

.app{
      display: flex;
      justify-content: center;
      align-items: center;
      width: 500px;
      height: 240px;
      margin: 20px auto;
      background: url('./test.jpg') no-repeat;
      background-size: contain;
    }
    .box {
      position: relative;
      width: 200px;
      height: 80px;
      text-align: center;
      line-height: 80px;
      overflow:hidden
    }

before伪元素设置背景图片的位置、大小、固定方式，after伪元素负责增加一个rgba的背景色

 .box::before{
      content: "";
      position: absolute;
      top: -100px;
      left: -100px;
      right: -100px;
      bottom: -100px;
      background: url('./test.jpg') center center no-repeat;
      background-attachment: local;
      background-size: 500px 240px;
      filter: blur(6px);
      z-index: -1;
    }
 .box::after{
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background-color: rgba(255,255,255,.5);
      z-index: 10;
    }

Firefox测试如图