i would like act a div as overlay sidebar only on mobile device. Other than mobile device it should act as normal div.

Sample Code:

```
<div class="row">
   <div class="col-lg-3" id="sidebar">
     overlay sidebar only on mobile device
   </div>
   <div class="col-lg-9 col-12">
   </div>
</div>

```

how do i make `id="sidebar"` act as normal div and sidebar on mobile device.