vue中怎么引入css vue中怎么引入bootstrap

$ npm install jquery --save-dev

+ const webpack = require("webpack");
module.exports = {
    entry: './index.js',
    output: {
        path: path.join(__dirname, './dist'),
        publicPath: '/dist/',
        filename: 'index.js'
    },
  + plugins: [
        new webpack.ProvidePlugin({
            jQuery: 'jquery',
            $: 'jquery'
        })
    ]
}

import $ from 'jquery' ;

<template>
  <div>
   Hello world！
  </div>
</template>
<script>
$(function () {  
    alert(123);  
 }); 
export default {
  
};
</script>
<style>
</style>

$ npm install --save-dev bootstrap

import './node_modules/bootstrap/dist/css/bootstrap.min.css';
import './node_modules/bootstrap/dist/js/bootstrap.min.js';

  <div class="btn-group" role="group" aria-label="...">  
      <button type="button" class="btn btn-default">Left</button>  
      <button type="button" class="btn btn-default">Middle</button>  
      <button type="button" class="btn btn-default">Right</button>  
    </div>