npm install vue@next element-plus

import { createApp } from 'vue';import ElementPlus from 'element-plus';import 'element-plus/lib/theme-chalk/index.css';
const app = createApp(App);app.use(ElementPlus);app.mount('#app');

<template>  <el-container>    <el-aside width="200px">侧边栏</el-aside>    <el-container>      <el-header>头部</el-header>      <el-main>主要内容区域</el-main>      <el-footer>底部</el-footer>    </el-container>  </el-container></template>

<template>  <ResponsiveLayout /></template>
<script>import ResponsiveLayout from './components/ResponsiveLayout.vue';
export default {  components: { ResponsiveLayout }};</script>

<template>  <el-container>    <el-aside width="200px">侧边栏</el-aside>    <el-container>      <el-header>        <el-button @click="toggleTheme">切换主题</el-button>      </el-header>      <el-main>主要内容区域</el-main>      <el-footer>底部</el-footer>    </el-container>  </el-container></template>
<script>export default {  data() {    return { isDark: false };  },  methods: {    toggleTheme() {      this.isDark = !this.isDark;      document.body.classList.toggle('dark-theme', this.isDark);    }  }};</script>

<template>  <el-form>    <el-form-item label="用户名">      <el-input v-model="username" />    </el-form-item>    <el-form-item label="密码">      <el-input type="password" v-model="password" />    </el-form-item>    <el-button type="primary" @click="submitForm">提交</el-button>  </el-form></template>
<script>export default {  data() {    return { username: '', password: '' };  },  methods: {    submitForm() {      alert(`提交内容：\n用户名: ${this.username}, 密码: ${this.password}`);    }  }};</script>