HTML – 改变了我的div的宽度,现在中心消失了

我添加了一个背景色为绿色的div.我减小了宽度,因为我不希望它覆盖整个宽度.

但是现在div正在左边对齐!

网址:http://185.123.96.102/~kidsdrum/moneynest.co.uk/

HTML

<div class="jumbotron">
  <div class="container text-center">
    <div class="h1extrapadding hidden-xs hidden-sm"></div>  <h1 class="boldme">Aged 20-30 & frustrated with money?</h1> 
    <div class="greenpromobox">
    <div class="h2extrapadding hidden-xs hidden-sm"></div>  <h2 class="boldme">Take our free <b class="jumpstarttext">Jumpstart Your Finances</b> class to<br /> quickly gain control over your finances</h2>
     <p class="text-center">
               <br>
            <!-- Begin MailChimp Signup Form -->
<div id="mc_embed_signup">
<form action="//moneynest.us11.list-manage.com/subscribe/post?u=9ccf2d2219536b32eaae3c3d1&amp;id=299de51b4e" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate>
    <div id="mc_embed_signup_scroll">


                   <img src="http://185.123.96.102/~kidsdrum/moneynest.co.uk/img/hand-drawn-arrow.png" id="handarrow" class="hidden-xs hidden-sm" alt="arrow"><input type="email" value="" name="EMAIL" class="email" id="mce-EMAIL" placeholder="Enter your email address" required autofocus>
    <!-- real people should not fill this in and expect good things - do not remove this or risk form bot signups-->
    <div style="position: absolute; left: -5000px;" aria-hidden="true"><input type="text" name="b_9ccf2d2219536b32eaae3c3d1_299de51b4e" tabindex="-1" value=""></div>
    <div class="clear"><input type="submit" value="Start Class Now" name="subscribe" id="mc-embedded-subscribe" class="text-uppercase btn btn-primary btn-lg"></div>
    </div>
</form>
</div>

<!--End mc_embed_signup-->

</div>
</div>

 </div>
</div>

CSS

 .greenpromobox {
background-color: green;
 padding-top: 1px; 
 margin-top:25px;
  width: 70%; 
  border-radius: 5px;
  text-align: center;
 }

最佳答案 您将宽度减小到70%然后需要margin-left和margin-right auto

.greenpromobox {
      background-color: green;
      padding-top: 1px; 
      margin-top:25px;
      margin-left: auto;
      margin-right: auto;
      width: 70%; 
      border-radius: 5px;
      text-align: center;
 }
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