Javascript 下拉列表位于引导3中的面板下方

我的html是：

<div class="row" style="width: 500px">
    <div class="col-md-1">
        <div class="dropup" style="position: fixed; top: 200px">
            <button class="btn btn-danger dropdown-toggle" type="button" id="dropdownMenu2" data-toggle="dropdown" aria-expanded="true">
            Dropdown
            <span class="caret"></span>
            </button>
            <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu2">
                <li><a role="menuitem" href="#">Action</a></li>
                <li><a role="menuitem" href="#">Another lonnnnnnnnnnnnnn action</a></li>
                <li><a role="menuitem" href="#">Something else here</a></li>
                <li><a role="menuitem" href="#">Separated link</a></li>
            </ul>
        </div>
    </div>
    <div class="col-md-11">
        <div class="panel panel-default">
            <div class="panel-body">
                <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Adipisci enim architecto debitis saepe veritatis, nesciunt neque dolorem reprehenderit! Officiis, optio. Ipsum quisquam, ut, nemo cupiditate quaerat laudantium nostrum tempore reiciendis! Nisi molestias autem et, aliquid eligendi esse obcaecati aliquam, sed repellat hic qui, consequatur eum explicabo magnam error. Explicabo ex vitae laboriosam dolores molestiae animi, temporibus quam perspiciatis sint ea amet doloremque repudiandae magni placeat porro, delectus laudantium beatae facere, omnis quisquam hic! Eum sed qui laboriosam natus dolorem nam vel deserunt excepturi repellat vero odit sapiente optio fugit ratione, minima sequi facilis numquam, ullam hic quo. Nam, atque, voluptates!</p>
            </div>
        </div>
    </div>
</div>

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当我运行它时，下拉菜单在面板下面。如何修复面板是在下拉按钮和下拉菜单项下？

正如我所说，您必须使用z-index

在哪里换车

<div class="dropup" style="position: fixed; top: 200px; z-index: 9999;">

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玩z-index规则，也许可以删除溢出：隐藏形式它的parentz下拉索引默认为1000，面板没有z-index

<div class="dropup" style="position: fixed; top: 200px; z-index: 9999;">