how to select class name from button of span in below code as follows : how to select class name from button of span in below code as follows 
```
<span class="input-group-btn-vertical">   
   <button class="btn btn-white bootstrap-touchspin-up " type="button">+</button>   
   <button class="btn btn-white bootstrap-touchspin-down " type="button">-</button></span>
```