bootstrap绝对定位写法

以侧边导航栏为例

html代码

<!-- 侧边导航栏 -->
<div class="row sidebar">
    <div class="col-md-12">
        <div class="row">
         ...
        </div>
    </div>
</div>

css代码

    <style>
    .sidebar{position: relative;}       
    .sidebar >.col-md-12{
        position: absolute;
        z-index: 100;
        background:#FFF;    
    }
    </style>