顶部自动显示阴影

 

// 顶部自动显示底部阴影

.header_top_div_box {

  width: 100%;

  position: relative;

}

// 遮挡物

.header_top_div_box::after {

  content: '';

  width: 100%;

  height: 10px;

  position: absolute;

  top: 0;

  display: inline-block;

  background-color: #f1f1f1;

  z-index: 1000;

}

// 阴影

.header_top_div_box::before {

  content: '';

  box-shadow: 0 0 5px 1px #909399;

  position: fixed;

  top: 0;

  width: 100%;

  z-index: 999;

}