css - 子元素跑到父元素外面

真的很奇怪 我也不知道什么鬼

mine.vue

topnav.vue

index.html

index.js

import Vue from 'vue'
import VueRouter from 'vue-router'

import topNav from '../components/topNav'
import mine from '../components/mine'


Vue.use(VueRouter)

const router = new VueRouter({
    routes: [
        {
            path: '/mine',
            component: mine
        }
    ]
})
export default router

app/index.js

import Vue from 'vue'
import router from '../router'
import topnav from '../components/topNav'
require("../style/index.css?1.2.1")

var app = new Vue({
    el: "#app1",
    components: {
        topnav
    },
    router
})