$(document).ready(function(){
  if (firefoxVersion() < 3.5)
    $("#browser-warning").css('display', 'block');
});

function firefoxVersion() {
  if (/Firefox[\/\s](\d+\.\d+)/.test(navigator.userAgent)){
  var ffversion = new Number(RegExp.$1);
  if (ffversion>=3.5)
    return 3.5;
  else if (ffversion>=3)
    return 3;
  else if (ffversion>=2)
    return 2;
  else if (ffversion>=1)
    return 1;
  } else
   return -1;
}