How to hide a in a <select> menu with CSS?

Answer 1

Late to the game, but most of these seem quite complicated.

Here's how I did it:

var originalSelect = $('#select-2').html();

// filter select-2 on select-1 change
$('#select-1').change(function (e) {

    var selected = $(this).val();

    // reset select ready for filtering
    $('#select-2').html(originalCourseSelect);

    if (selected) {
        // filter
        $('#select-2 option').not('.t' + selected).remove();
    }

});

markup of select-1: