$(document).ready(function () {
var m1 = 155;   var m2 = 10; var s = $('.top-menu'); s.css({top: m1});
function margin() {
    var top = $(window).scrollTop();
    if (top+m2 < m1) { s.css({top: m1-top}); } else { s.css({top: m2});  }
  }
  $(window).scroll(function() { margin(); })
});