常用flex布局-css

水平排列

    .wrapper { 
      display: flex;
      flex-wrap: wrap;
      justify-content: space-between; 
    }
    .item {
      width: 30%;
      height: 24px; 
    }
    .wrapper::after {
      content: "";
      width: 30%;
    }

不知道行高的时候垂直居中

    .vertical-center { 
      display: flex;
      justify-content: center;
      align-items: center;
    }