效果图
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>demo01</title> <link rel="stylesheet" href="css/bootstrap.min.css" /> <script type="application/javascript" src="js/jquery-1.11.1.min.js"></script> <script language="JavaScript" src="js/bootstrap.min.js"></script> </head> <body> <div class="container"> <hr/> <div class="btn-group"> <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown"> 下拉 <span class="caret"></span> </button> <ul class="dropdown-menu"> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> </ul> </div> <div class="btn-group"> <button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown"> 下拉 <span class="caret"></span> </button> <ul class="dropdown-menu"> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> </ul> </div> <div class="btn-group"> <button type="button" class="btn btn-info dropdown-toggle" data-toggle="dropdown"> 下拉 <span class="caret"></span> </button> <ul class="dropdown-menu"> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> </ul> </div> <div class="btn-group"> <button type="button" class="btn btn-default dropdown-toggle btn-lg" data-toggle="dropdown"> 下拉 <span class="caret"></span> </button> <ul class="dropdown-menu"> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> </ul> </div> <hr /> <div class="btn-group dropup" > <button type="button" class="btn btn-default">下拉</button> <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown"> <span class="caret"></span> </button> <ul class="dropdown-menu"> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> <li><a href="#">项目</a></li> </ul> </div> </div> </body> </html>