Bootstrap-风格的下拉按框：Bootstrap Select

<select class="selectpicker" data-style="btn-primary">
...
</select>
  
<select class="selectpicker" data-style="btn-info">
...
</select>
  
<select class="selectpicker" data-style="btn-success">
...
</select>
  
<select class="selectpicker" data-style="btn-warning">
...
</select>
  
<select class="selectpicker" data-style="btn-danger">
...
</select>
  
<select class="selectpicker" data-style="btn-inverse">
...
</select>