function changeNav(t){
  var l1=document.getElementById('l1');
  var l2=document.getElementById('l2');
  if (t=='s'){
    l1.className='summerred';
    l2.className='wintergray';
    createCookie('nav', 's', 3600);
  } else{
    l1.className='summergray';
    l2.className='winterred';
    createCookie('nav', 'w', 3600);
	window.location.href = 'http://www.pneumatiky-prodej-pneu.cz';
	return;
  }
  window.location.href = window.location.href;
}
function bv(kat){
	var podmenu;
	if (podmenu = document.getElementById("v"+kat)){podmenu.style.fontWeight='bold';}
}
function b(kat){
	var podmenu;
	if (podmenu = document.getElementById("c"+kat)){podmenu.style.fontWeight='bold';}
}
function createCookie(name,value,seconds){
	if (seconds){
		var date = new Date();
		date.setTime(date.getTime()+(seconds*1000));
		var expires = "; expires="+date.toGMTString();
	}
	else var expires = "";
	document.cookie = name+"="+value+expires+"; path=/";
}
function checkMailSend(t) {
  if (!t.email.value){
    alert ("Položka Email není v požadovaném formátu.");
    t.email.focus();
    return false;
  } 
  var reg1 = /(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/; // not valid email
  var reg2 = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/; // valid email
  if (t.email.value && ( reg1.test(t.email.value) || !reg2.test(t.email.value) )) { // if syntax is valid
    alert ("Položka Email není v požadovaném formátu.");
    t.email.focus();
    return false;
  }
	return true;
}
function checkForm(t) {
	if (!ChkInput(t.q0, "Množství", set_numeric, 0))  return false;
	return true;
}