<div class="btn-group">
	<button type="button" class="dropdown-toggle">Action</button>
	<ul class="dropdown-menu">
		<li><a href="#">Action</a></li>
		<li><a href="#">Another action</a></li>
		<li><a href="#">Something else here</a></li>
	</ul>
</div>


Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse dapibus velit eu cursus facilisis. Curabitur lobortis mi orci, at gravida orci placerat non. Aenean tristique condimentum luctus. Maecenas eget dolor nunc. Ut non bibendum arcu, at tempor lacus. Nam bibendum nisi porta turpis volutpat gravida. Praesent efficitur dolor diam, sed luctus lorem lobortis at. Phasellus in urna tincidunt, aliquam velit eu, ultricies nunc. Etiam efficitur metus sed lectus congue ullamcorper. Maecenas consectetur egestas ex non cursus. Vestibulum sit amet aliquam elit. Quisque vitae nibh elementum, rhoncus ex vitae, semper nunc. Praesent in tempus lacus. Phasellus venenatis laoreet nibh, placerat tristique turpis commodo sit amet. Vestibulum imperdiet quis dolor sit amet euismod. Sed vulputate nisl accumsan dapibus euismod.
.btn-group {
	position: relative;
	display: inline-block;
	vertical-align: middle;
}
.dropdown-menu {
	position:absolute;
	/*top:100%; */
	margin-top:5px;
}



/*////////偷懒一下,效果直接用了背景图,:-P:-P////////*/
.dropdown-toggle {
	display: inline-block;
	width: 83px;
	height: 34px;
	background: url(http://imgcache.qq.com/open_proj/proj_qcloud_v2/bee/docs/css/img/sample-3.png) 0 0 no-repeat;
	font-size: 0;
	border: 0;
}
.dropdown-menu{
	width:185px;
	height:144px;
	background: url(http://imgcache.qq.com/open_proj/proj_qcloud_v2/bee/docs/css/img/sample-2.png) 0 0 no-repeat;
	font-size:0;
	margin-left:-6px;
}
Rerun