in themes/kube/static/js/kube.js [287:292]
revertHideClasses: function()
{
if (this.$element.data('hide-sm-class')) this.$element.addClass('hide-sm').removeData('hide-sm-class');
else if (this.$element.data('hide-md-class')) this.$element.addClass('hide-md').removeData('hide-md-class');
else this.$element.addClass('hide');
},