先看效果

• 未设置样式之前：布局没有充满整个页面，而且布局高度会随着左边菜单内容的展开而变化

• 设置样式后：布局充满整个页面，左边菜单内容展开后也不会影响布局高度，左边菜单内容超出页面高度时会自动添加滚动条

 项目结构目录：

设置样式之前代码： 

App.vue

<template>
  <Home/>
</template>

<script>
import Home from './components/Home.vue'

export default {
  name: 'App',
  components: {
    Home
  }
}
</script>

<style>
@import './assets/css/reset.css';
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
}
</style>

 Home.vue   

<template>
  <div  class="home">
    <el-container>
      <el-header><Header/></el-header>
      <el-container class="content">
        <Menu/>
        <el-container>
          <el-main>Main</el-main>
          <el-footer><Footer/></el-footer>
        </el-container>
      </el-container>
    </el-container>
  </div>
</template>

<script setup>
import Header from '../components/common/Header.vue'
import Menu from '../components/common/Menu.vue'
import Footer from '../components/common/Footer.vue'
</script>

<style scoped lang="less">
.home{
  .el-container{
    .el-header{
     background-color: #CCCCFF;
   }
    .el-footer{
      background-color: #CCFFFF;
    }
    .el-main{
      background-color: #FFCCCC;
    }
  }
}
</style>

代码来源于element plus中Container 布局容器

Menu.vue

<template>
    <div class="menu">
      <el-aside width="200px">
      <el-menu
        active-text-color="#ffd04b"
        background-color="#66CCCC"
        class="el-menu-vertical-demo"
        default-active="2"
        text-color="#fff"
        @open="handleOpen"
        @close="handleClose"
      >
        <el-sub-menu index="1">
          <template #title>
            <el-icon><location /></el-icon>
            <span>Navigator One</span>
          </template>
          <el-menu-item-group title="Group One">
            <el-menu-item index="1-1">item one</el-menu-item>
            <el-menu-item index="1-2">item two</el-menu-item>
          </el-menu-item-group>
          <el-menu-item-group title="Group Two">
            <el-menu-item index="1-3">item three</el-menu-item>
          </el-menu-item-group>
          <el-sub-menu index="1-4">
            <template #title>item four</template>
            <el-menu-item index="1-4-1">item one</el-menu-item>
          </el-sub-menu>
        </el-sub-menu>
        <el-menu-item index="2">
          <el-icon><icon-menu /></el-icon>
          <span>Navigator Two</span>
        </el-menu-item>
        <el-menu-item index="3" disabled>
          <el-icon><document /></el-icon>
          <span>Navigator Three</span>
        </el-menu-item>
        <el-menu-item index="4">
          <el-icon><setting /></el-icon>
          <span>Navigator Four</span>
        </el-menu-item>
        <el-sub-menu index="5">
          <template #title>
            <el-icon><location /></el-icon>
            <span>Navigator One</span>
          </template>
          <el-menu-item-group title="Group One">
            <el-menu-item index="1-1">item one</el-menu-item>
            <el-menu-item index="1-2">item two</el-menu-item>
          </el-menu-item-group>
          <el-menu-item-group title="Group Two">
            <el-menu-item index="1-3">item three</el-menu-item>
          </el-menu-item-group>
          <el-sub-menu index="1-4">
            <template #title>item four</template>
            <el-menu-item index="1-4-1">item one</el-menu-item>
          </el-sub-menu>
        </el-sub-menu>
      </el-menu>
      </el-aside>
    </div>
</template>
<script setup>
import {
  Document,
  Menu as IconMenu,
  Location,
  Setting,
} from '@element-plus/icons-vue'
const handleOpen = (key, keyPath) => {
  console.log(key, keyPath)
}
const handleClose = (key, keyPath) => {
  console.log(key, keyPath)
}
</script>
<style lang="less" scoped>

</style>

代码来源于element plus中Menu 菜单

 设置样式：

分别在Home.vue和Menu.vue中添加以下样式即可

Home.vue

<style scoped lang="less">
.home{
  .el-container{
    // 新加的样式 实现绝对定位
    .content{
      position: absolute;
      top:60px;
      bottom: 0;
      width: 100%;
    }
    .el-header{
     background-color: #CCCCFF;
   }
    .el-footer{
      background-color: #CCFFFF;
    }
    .el-main{
      background-color: #FFCCCC;
    }
  }
}
</style>

Menu.vue

<style lang="less" scoped>
.menu{
  .el-aside{
    height: 100%;
    .el-menu{
      height: 100%;
    }
  }
}
</style>

注：若只添加了Home.vue样式则会出现以下效果，menu没有充满页面