Bootstrap中心对齐下拉​​菜单

Question

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

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;
}

Answer 1

你需要将下拉菜单和切换按钮放在一个.btn-group.

此外,Bootstrap提供了对齐内容的.text-center属性.这可以用来.school-options-dropdown代替手动添加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>

Answer 2

我在尝试解决类似问题时发现了这一点。感谢弗拉基米尔·罗德金

.dropdown-menu-center {
right: auto;
left: 50%;
-webkit-transform: translate(-50%, 0);
-o-transform: translate(-50%, 0);
transform: translate(-50%, 0);}

https://jsfiddle.net/VovanR/2ao5b22h/

Answer 3

如果你不想改变你的html代码，这是css将解决你的问题：

.dropdown {text-align:center;}
.button, .dropdown-menu {margin:10px auto}
.dropdown-menu {width:200px; left:50%; margin-left:-100px;}

jsfiddle.net 上的示例。