function ac(kaynak){
document.getElementById(kaynak).style.display = 'block';
}
function kapat(kaynak){
	document.getElementById(kaynak).style.display = 'none';
}

function vac(kaynak){
	document.getElementById(kaynak).style.visibility = 'visible';
}

function vkapat(kaynak){
	document.getElementById(kaynak).style.visibility = 'hidden';
}

/* browser */
// FIREFOX
if (/Firefox[\/\s](\d+\.\d+)/.test(navigator.userAgent)){ //test for Firefox/x.x or Firefox x.x (ignoring remaining digits);
 var ffversion=new Number(RegExp.$1) // capture x.x portion and store as a number
 if (ffversion>=3)
  document.write("")
}
// INTERNET EXPLORER
else if (/MSIE (\d+\.\d+);/.test(navigator.userAgent)){ //test for MSIE x.x;
 var ieversion=new Number(RegExp.$1) // capture x.x portion and store as a number
 if (ieversion>=8)
  document.write()
 else if (ieversion>=7)
  document.write("<link href=css/IE7.css rel=stylesheet type=text/css />")
 else if (ieversion>=6)
  document.write("<link href=css/IE6.css rel=stylesheet type=text/css />")
}
// OPERA
else if (/Opera[\/\s](\d+\.\d+)/.test(navigator.userAgent)){ //test for Opera/x.x or Opera x.x (ignoring remaining decimal places);
 var oprversion=new Number(RegExp.$1) // capture x.x portion and store as a number
 if (oprversion>=1)
  document.write()
}
else
 document.write()