css: {
    preprocessorOptions: {
      scss: {
        additionalData: `@import "./src/assets/style/element-plus-var.scss";`,
      },
    },
  },
.............
styleImport({
    libs: [
      {
        libraryName: 'element-plus',
        esModule: true,
        resolveStyle: (name) => {
          name = name.substr(3)
          return `element-plus/packages/theme-chalk/src/${name}.scss`
        },
        resolveComponent: (name) => {
          return `element-plus/lib/${name}`
        },
      },
    ],
  }),