Sandbox for testing your grid. Make sure stylesheet and classes reflect your grid (i.e. grid12.css for 12 col).

.col-xs-12 .col-md-8
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6 .col-md-4
.col-xs-6
.col-xs-6

Responsive Utility Test

✔ Visible on x-small
✔ Visible on small
Medium ✔ Visible on medium
✔ Visible on large