参考：https://blog.csdn.net/dcxia89/article/details/80402490
         https://blog.csdn.net/jianglibo1024/article/details/61916954

以element-ui 的日期选择器为例

<style>   //关键：另起样式，不加scoped
    .el-popper {
        position: absolute;
        top: 1.46rem !important;  //关键：加!important
        left: .25rem !important;
    }
</style>