在上使用
justify-content-center帮助程序类
form。这将使内容与flex属性居中
justify-content:center;
#home{ background-image: url('../img/jumbotron-bkg-2.jpg'); margin-top: 50px; text-align: center;}<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" rel="stylesheet"/><div id="home"> <h1 >My Awesome App!</h1> <p >This is why you should download this fantastic app!</p> <hr > <p>Want to know more? Join our mailing list!</p> <form > <label for="yourEmail">Email</label> <div > <div >@</div> <input type="text" id="yourEmail" placeholder="Your Email"> </div> <button type="button" >Sign Up</button> </form></div>
