这个问题在这里已有答案：
我正在尝试向jumbotron添加背景图像，我已经看到了很多示例，但在代码中似乎没有任何工作。
在src下创建了css文件夹
<template>
<div class="development container">
<div class="jumbotron mt-3">
<h1 class="display-3">Sofware Development</h1>
CSS文件代码.jumbotron mt-3 {
background-image: url('../empowers/src/assets/team1.jpg');
background-size: cover;
height: 100%;}
.jumbotron{
background-image: url('http://placehold.jp/006699/cccc00/150x100.png');
background-size: cover;
height: 100%;}<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<div class="development container">
<div class="jumbotron mt-3">
<h1 class="display-3">Sofware Development</h1>
</div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
</body>
</html>你只需要使用jumbotron作为一个类来应用背景图像。
如下：
.jumbotron {
background-image: url('http://getbootstrap.com/docs/4.3/assets/brand/bootstrap-social.png');
background-size: cover;
height: 100%;
}<div class="development container">
<div class="jumbotron mt-3">
<h1 class="display-3">Sofware Development</h1>
</div>
</div>