elementUI el-card的头部样式在scoped下作用无效

<style scoped>
.el-card /deep/ .el-card__body {
    padding: 6px;
  }
 .el-card /deep/ .el-card__header {
    padding: 8px 20px;
    border-bottom: 1px solid #EBEEF5;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
    font-size: 16px;
    background-color: lightgrey;
}
</style>