Hi Anton,
$('#gt').click(function() { //<-- # this is wrong, you don't have a gt #id but a gt.class so you have to change #gt in .gt
$(this).removeClass("gt");
$(this).addClass("gt_active");
});
this should work:
$('.gt').click(function() {
$(this).removeClass("gt");
$(this).addClass("gt_active");
});
try it,
regards
Diego