Is a way to blur colorbox overlay?

Is a way to blur colorbox overlay?

I try to add css:

#cboxOverlay {
  backdrop-filter: blur(10px);
}

but it's not work in Firefox.

So i add script:

(function($) {
    Drupal.behaviors.mytheme1Behavior = {
        attach: function(context, settings) {

            $.colorbox({
                onComplete: function() {
                    $("body").addClass("blured");
                },

                onCleanup: function() {
                    $("body").removeClass("blured");
                }
            });

        }
    };
})(jQuery, Drupal);

yes, this script works, but I see colorbox glitch on every page load :(

Mb i do something wrong?