how can we write jquery only for apple OS X Snow Leopard with some css ?

how can we write jquery only for apple OS X Snow Leopard with some css ?

Hi all,
I use some jquery  for a simple height maintain for all width resolution. but in this particular operating system of apple that is not working after 1600*1200px. please give me any idea for fix it .

this is my script which i am using in page.

$(document).ready(function () {

    $(window).resize(function () {
      var current_height = $('.home_slider').height();
      var mgbottom = "";
      if (current_height >= 300) {
        mgbottom = (current_height - 300) + 15;
      } else {
        mgbottom = 10;
      }

      $('.find_minder').css("marginBottom", mgbottom + "px");
    });
  });

please give me any idea how i can write for OS X Snow Leopard , same functionality. this is working in all other OS .