elment plus 官方主题覆盖教程不生效，怎么办呢？

https://element-plus.gitee.io/zh-CN/guide/theming.html#如何覆盖它？
上面是官方给出的教程，
我根据教程，生成scss文件并且在main.ts中引入，但并不生效，请问怎么办呢？

// @/index.scss
@forward 'element-plus/theme-chalk/src/common/var.scss' with (
  $colors: (
    'primary': (
      'base': #67c23a
    )
  )
);
@use 'element-plus/theme-chalk/src/index.scss' as *;

//main.ts
import { createApp } from 'vue'
import App from './App.vue'
import router from './router'
import store from './store'
//引入index.scss
import './index.scss'
import * as ELIcons from '@element-plus/icons-vue'
const app = createApp(App)
for (let iconName in ELIcons) {
  app.component(iconName, ELIcons[iconName])
}

app.use(store).use(router).mount('#app')

main.ts中未引入element-plus，需添加代码：

import ElementPlus from "element-plus";
app.use(store).use(router).use(ElementPlus).mount("#app");