function browser_detect()
{
  // Browser Detect  v2.1.6
  // documentation: http://www.dithered.com/javascript/browser_detect/index.html
  // license: http://creativecommons.org/licenses/by/1.0/
  // code by Chris Nott (chris[at]dithered[dot]com)
  var ua = navigator.userAgent.toLowerCase();

  // browser engine name
  this.isGecko = (ua.indexOf('gecko') != - 1 && ua.indexOf('safari') == - 1);
  this.isAppleWebKit = (ua.indexOf('applewebkit') != - 1);

  // browser name
  this.isKonqueror = (ua.indexOf('konqueror') != - 1);
  this.isSafari = (ua.indexOf('safari') != - 1);
  this.isOmniweb = (ua.indexOf('omniweb') != - 1);
  this.isOpera = (ua.indexOf('opera') != - 1);
  this.isIcab = (ua.indexOf('icab') != - 1);
  this.isAol = (ua.indexOf('aol') != - 1);
  this.isIE = (ua.indexOf('msie') != - 1 && ! this.isOpera && (ua.indexOf('webtv') == - 1));
  this.isMozilla = (this.isGecko && ua.indexOf('gecko/index.html') + 14 == ua.length);
  this.isFirebird = (ua.indexOf('firebird/index.html') != - 1);
  this.isFirefox = (ua.indexOf('firefox/index.html') != - 1); // scotts
  this.isNS = ((this.isGecko) ? (ua.indexOf('netscape') != - 1) : ((ua.indexOf('mozilla') != - 1)
              && ! this.isOpera 
              && ! this.isSafari 
              && (ua.indexOf('spoofer') == - 1)
              && (ua.indexOf('compatible') == - 1)
              && (ua.indexOf('webtv') == - 1)
              && (ua.indexOf('hotjava') == - 1)));

  // spoofing and compatible browsers
  this.isIECompatible = ((ua.indexOf('msie') != - 1) && ! this.isIE);
  this.isNSCompatible = ((ua.indexOf('mozilla') != - 1) && ! this.isNS && ! this.isMozilla);

  // rendering engine versions
  this.geckoVersion = ((this.isGecko) ? ua.substring((ua.lastIndexOf('gecko/index.html') + 6),(ua.lastIndexOf('gecko/index.html') + 14)) : - 1);
  this.equivalentMozilla = ((this.isGecko) ? parseFloat(ua.substring(ua.indexOf('rv:') + 3)) : - 1);
  this.appleWebKitVersion = ((this.isAppleWebKit) ? parseFloat(ua.substring(ua.indexOf('applewebkit/index.html') + 12)) : - 1);

  // browser version
  this.versionMinor = parseFloat(navigator.appVersion);

  // correct version number
  if (this.isGecko && ! this.isMozilla)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('index.html', ua.indexOf('gecko/index.html') + 6) + 1));
  }
  else if (this.isMozilla)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('rv:') + 3));
  }
  else if (this.isIE && this.versionMinor >= 4)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('msie ') + 5));
  }
  else if (this.isKonqueror)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('konqueror/index.html') + 10));
  }
  else if (this.isSafari)
  {
    this.versionMinor = parseFloat(ua.substring(ua.lastIndexOf('safari/index.html') + 7));
  }
  else if (this.isOmniweb)
  {
    this.versionMinor = parseFloat(ua.substring(ua.lastIndexOf('omniweb/index.html') + 8));
  }
  else if (this.isOpera)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('opera') + 6));
  }
  else if (this.isIcab)
  {
    this.versionMinor = parseFloat(ua.substring(ua.indexOf('icab') + 5));
  }

  this.versionMajor = parseInt(this.versionMinor);
  // dom support
  this.isDOM1 = (document.getElementById);
  this.isDOM2Event = (document.addEventListener && document.removeEventListener);

  // css compatibility mode
  this.mode = document.compatMode ? document.compatMode : 'BackCompat';

  // platform
  this.isWin = (ua.indexOf('win') != - 1);
  this.isWin32 = (this.isWin && (ua.indexOf('95') != - 1 
                  || ua.indexOf('98') != - 1 
                  || ua.indexOf('nt') != - 1 
                  || ua.indexOf('win32') != - 1 
                  || ua.indexOf('32bit') != - 1
                  || ua.indexOf('xp') != - 1));
  this.isMac = (ua.indexOf('mac') != - 1);
  this.isUnix = (ua.indexOf('unix') != - 1 
                  || ua.indexOf('sunos') != - 1 
                  || ua.indexOf('bsd') != - 1 
                  || ua.indexOf('x11') != - 1)
  this.isLinux = (ua.indexOf('linux') != - 1);

  // specific browser shortcuts
  this.isNS4x    = (this.isNS && this.versionMajor == 4);
  this.isNS40x   = (this.isNS4x && this.versionMinor < 4.5);
  this.isNS47x   = (this.isNS4x && this.versionMinor >= 4.7);
  this.isNS4up   = (this.isNS && this.versionMinor >= 4);
  this.isNS6x    = (this.isNS && this.versionMajor == 6);
  this.isNS6up   = (this.isNS && this.versionMajor >= 6);
  this.isNS7x    = (this.isNS && this.versionMajor == 7);
  this.isNS7up   = (this.isNS && this.versionMajor >= 7);

  this.isIE4x    = (this.isIE && this.versionMajor == 4);
  this.isIE4up   = (this.isIE && this.versionMajor >= 4);
  this.isIE5x    = (this.isIE && this.versionMajor == 5);
  this.isIE55    = (this.isIE && this.versionMinor == 5.5);
  this.isIE5up   = (this.isIE && this.versionMajor >= 5);
  this.isIE6x    = (this.isIE && this.versionMajor == 6);
  this.isIE6up   = (this.isIE && this.versionMajor >= 6);
  this.isIE4xMac = (this.isIE4x && this.isMac);
}

var ua = new browser_detect();