<div class="container" style="border:1px solid red;"> 
 <div class="row"> 
  <div class="col-lg-3 col-sm-4 col- xs-6"> 
   <div class="thumbnail"> 
    <img src="img/codeguide.png"> 
    <h2>靠谱研究所</h2> 
    <p>我们的口号是：靠谱、有趣、有料</p> 
   </div> 
  </div> 
  <div class="col-lg-3 col-sm-4 col- xs-6"> 
   <div class="thumbnail"> 
    <img src="img/codeguide.png"> 
    <h2>靠谱研究所</h2> 
    <p>我们的口号是：靠谱、有趣、有料</p> 
   </div> 
  </div> 
 </div>  
 </div> 

<span style="white-space:pre"> </span> <h1 class="text-primary">text-primary靠谱研究所</h1> 
  <h1 class="text-success">text-success靠谱研究所</h1> 
  <h1 class="text-warning">text-warning靠谱研究所</h1> 
  <h1 class="text-danger">text-danger靠谱研究所</h1> 
  <h1 class="text-info">text-info靠谱研究所</h1> 
  <h1 class="text-muted">text-muted靠谱研究所</h1> 

<span style="white-space:pre"> </span> <h1 class="bg-primary">text-primary靠谱研究所</h1> 
  <h1 class="bg-success">text-success靠谱研究所</h1> 
  <h1 class="bg-warning">text-warning靠谱研究所</h1> 
  <h1 class="bg-danger">text-danger靠谱研究所</h1> 
  <h1 class="bg-info">text-info靠谱研究所</h1> 
  <h1 class="bg-muted">text-muted靠谱研究所</h1> 

<span style="white-space:pre"> </span> <!--关闭按钮--> 
  <button class="close"><span>×</span></button> 
  <!--三角图标--> 
  <span class="caret"></span> 

<div class="pull-left bg-primary">这是左边的内容</div> 
 <div class="pull-right bg-danger">这是右边的内容</div> 

<!--块元素垂直居中--> 
 <style> 
  #div2{ 
  position:absolute; 
  left:50%; 
  top:50%; 
  transform:translate(-50%,-50%);//平移 
  } 
 </style> 
<span style="white-space:pre"> </span><!--实现块元素水平居中--> 
 <div id="div1" class="center-block text-center" style="width:500px;border:1px solid red;">块元素水平居中</div> 
 <!--实现块元素垂直居中--> 
 <div id="div2" class="center-block text-center" style="width:500px;border:1px solid red;">块元素垂直居中</div> 

<table class="table table-striped table-hover table-bordered"><!--隔行换色、鼠标悬停、表格边框--> 
   <thead> 
    <tr class="danger"><!--表格颜色--> 
     <th>姓名：</th> 
     <th>性别：</th> 
     <th>年龄：</th> 
    </tr> 
   </thead> 
   <tbody> 
    <tr> 
     <td>张三</td> 
     <td>男</td> 
     <td>23</td> 
    </tr> 
    <tr> 
     <td>张三</td> 
     <td>男</td> 
     <td>23</td> 
    </tr> 
    <tr> 
     <td>张三</td> 
     <td>男</td> 
     <td>23</td> 
    </tr> 
   </tbody> 
  </table> 

 <ul class="list-group"> 
 <li class="list-group-item"> 
 靠谱研究所 
 <!--列表徽章--><span class="badge">10</span> 
 </li> 
 <li class="list-group-item list-group-item-success">IT研究所</li> 
 <li class="list-group-item list-group-item-warning">美食研究所</li> 
 <li class="list-group-item list-group-item-info">美妆研究所</li> 
</ul> 

<style> 
 .container{ 
  width:450px; 
  height:300px; 
  background:#ffffff; 
  position:absolute; 
  left:50%; 
  top:50%; 
  transform:translate(-50%,-50%); 
  border-radius:20px; 
 } 
 </style> 
<span style="white-space:pre"> </span><form role="form"> 
   <h3 class="text-center">靠谱研究所后台管理系统</h3> 
   <div class="form-group has-success has-feedback"> 
    <label for="user">用户名</label> 
    <input type="text" id="user" placeholder="请输入用户名" class="form-control"> 
    <span class="glyphicon glyphicon-ok form-control-feedback"></span> 
   </div> 
   <div class="form-group has-error has-feedback"> 
    <label for="pass">密码</label> 
    <input type="text" id="pass" placeholder="请输入密码" class="form-control"> 
    <span class="glyphicon glyphicon-remove form-control-feedback"></span> 
   </div> 
   <div class="checkbox"> 
    <label> 
     <input type="checkbox">请记住我 
    </label> 
   </div> 
   <button type="submit" class="btn btn-success btn-block">提交</button> 
  </form>