This is an extra EXTRA small grid for Twitter Bootstrap 3, which allows you to target devices smaller than 480px wide (although this number can easily be changed as necessary).
Save the xxs.scss into your current project, and then import it either into bootstrap.scss or into your main SCSS file.
@import 'xxs';
Use the same syntax as the regular Bootstrap grid.
<div class="col-xxs-12 col-xs-6 col-md-3">
...
</div>
The author is neither affiliated with nor endorsed by Twitter.