mui: shows that the relevant modules cannot be found, but I think there is no error in the path

sources of topics and their own ideas

main.js file

/ / Please paste the code text below (do not replace the code with pictures)

import Vue from "vue"
import App from "./App"
import VueRouter from "vue-router"
Vue.use(VueRouter)
import router from "./router.js"
import VueResource from "vue-resource"
Vue.use(VueResource)
import "./lib/mui/css/mui.min.css"
import "./lib/mui/css/icons-extra.css"

router.js

import VueRouter from "vue-router"

import HomeContainer from "./components/tarbar/HomeContainer"
import MemberContainer from "./components/tarbar/MemberContainer"
import ShopcarContainer from "./components/tarbar/ShopcarContainer"
import SearchContainer from "./components/tarbar/SearchContainer"

var router = new VueRouter({
routes:[
    { path:"/home",component:HomeContainer },
    { path:"/member",component:MemberContainer },
    { path:"/shopcar",component:ShopcarContainer },
    { path:"/search",component:SearchContainer }
],
linkActiveClass:"mui-active" //(router-link-active)
})


export default router

there are also mui.min.css and icons-extra.css in the file

error message

These relative modules were not found:

* ./lib/mui/css/mui.min.css in ./src/main.js
* ./lib/mui/css/icons-extra.css in ./src/main.js