我浪费了很多时间搜索一种方式来使我自己的xs大小(小于小)的输入和输入组，所以这里的代码！
更新2014/11/14
Peter Butkovic上传bug /请求到bootstrap github：
https://github.com/twbs/bootstrap/issues/15107
与他们的以下回应：
We won’t be adding it to v3 and I don’t think we’ll have the xs
buttons even in v4,but I’ll keep it in mind for that if we opt to
keep it around.
解决方法
对于输入小者：
.input-xs {
height: 22px;
padding: 2px 5px;
font-size: 12px;
line-height: 1.5; /* If Placeholder of the input is moved up,rem/modify this. */
border-radius: 3px;
}
输入组中的示例用法：
<div class="input-group">
<span class="input-group-btn">
<button class="btn btn-xs btn-success">
<i class="glyphicon glyphicon-plus"></i>
</button>
</span>
<input type="text" class="form-control input-xs" />
<span class="input-group-btn">
<button class="btn btn-xs btn-danger">
<i class="glyphicon glyphicon-minus"></i>
</button>
</span>
</div>
或者，您可以将类添加到输入组像这样：
.input-group-xs>.form-control,.input-group-xs>.input-group-addon,.input-group-xs>.input-group-btn>.btn {
height: 22px;
padding: 1px 5px;
font-size: 12px;
line-height: 1.5;
}
并使用：
<div class="input-group input-group-xs">
<span class="input-group-btn">
<button class="btn btn-success">
<i class="glyphicon glyphicon-plus"></i>
</button>
</span>
<input type="text" class="form-control" />
<span class="input-group-btn">
<button class="btn btn-danger">
<i class="glyphicon glyphicon-minus"></i>
</button>
</span>
</div>
.input-xs {
height: 22px!important;
padding: 2px 5px;
font-size: 12px;
line-height: 1.5;
border-radius: 3px;
}
.input-group-xs>.form-control,.input-group-xs>.input-group-btn>.btn {
height: 22px;
padding: 1px 5px;
font-size: 12px;
line-height: 1.5;
}
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
<div class="input-group">
<span class="input-group-btn">
<button class="btn btn-xs btn-success">
<i class="glyphicon glyphicon-plus"></i>
</button>
</span>
<input type="text" class="form-control input-xs" />
<span class="input-group-btn">
<button class="btn btn-xs btn-danger">
<i class="glyphicon glyphicon-minus"></i>
</button>
</span>
</div>
<br/>
<div class="input-group input-group-xs">
<span class="input-group-btn">
<button class="btn btn-success">
<i class="glyphicon glyphicon-plus"></i>
</button>
</span>
<input type="text" class="form-control" />
<span class="input-group-btn">
<button class="btn btn-danger">
<i class="glyphicon glyphicon-minus"></i>
</button>
</span>
</div>
