Bootstrap 中心对齐下拉​​菜单

我的页面中央有一个下拉按钮，但是当我单击下拉菜单时，实际的下拉部分仍然位于页面的左侧。有什么问题吗？

HTML

<div class="row">
    <div class="col-md-12 school-options-dropdown">
            <div class="dropdown">
              <button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Choose a School
              <span class="caret"></span></button>
              <ul class="dropdown-menu">
                  <li><a href="#">Add your school</a></li>
                  <li><a href="#">Hello</a></li>
              </ul>
            </div>
    </div>
</div>

CSS

div.school-options-dropdown {
    text-align: center;
}

.dropdown {
    text-align:center;
}

.dropdown-menu {
    text-align: center;
}

您需要将下拉菜单和切换按钮放在.btn-group.

此外，Bootstrap 还提供了.text-center财产 http://getbootstrap.com/css/#type-alignment来对齐内容。这可以用在.school-options-dropdown，而不是手动添加CSS。

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />


<div class="row">
  <div class="col-md-12 school-options-dropdown text-center">
    <div class="dropdown btn-group">

      <button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Choose a School
        <span class="caret"></span>
      </button>

      <ul class="dropdown-menu">
        <li><a href="#">Add your school</a></li>
        <li><a href="#">Hello</a></li>
      </ul>

    </div>
  </div>
</div>