function checkform(form) {
var len = form.email.value.length;
    var pos = form.email.value.lastIndexOf ( '.', len - 1 ) + 1;

if (form.email.value == "") {
    alert( "Please enter your email address." );
    form.email.focus();
    return false ;
  }
  else if (form.tresc.value.length <3) {
	 alert( "Please enter some description." );
    form.tresc.focus();
    return false ; 
  }
else if (form.email.value.indexOf ('@', 0) == -1)
{       alert( "Please enter valid email address." );
    form.email.focus();
    return false ;
}
else if (form.email.value.indexOf ('@', 0) < 1)
{       alert( "Please enter valid email address." );
    form.email.focus();
    return false ;
}
else if (form.email.value.indexOf ('.', 0) == -1)
{       alert( "Please enter valid email address." );
    form.email.focus();
    return false ;
}

else if (( len - pos ) < 2 || ( len - pos ) > 4 )
{       alert( "Please enter valid email address." );
    form.email.focus();
    return false ;
}else {
  return true ;
  }
}

function showdiv(pass, but) { 
changecolor(but);
var divs = document.getElementsByTagName('div'); 
for(i=0;i<divs.length;i++){ 
if(divs[i].id.match(pass)){//if they are 'see' divs 
if (document.getElementById) // DOM3 = IE5, NS6 
divs[i].style.display='block';// show/hide 
else 
if (document.layers) // Netscape 4 
document.layers[divs[i]].display = 'block'; 
else // IE 4 
document.all.divs[i].display = 'block'; 
}
else { 

if(divs[i].id in {'Firma':'','Partner':'','Klient':''})  {
if (document.getElementById) 
divs[i].style.display='none';
else 
if (document.layers) // Netscape 4 
document.divs[i].display='none';
else // IE 4 
document.all.divs[i].display='none';
} }
}

} 
function changecolor (i)
{
document.getElementById('faz').style.color = "white";
document.getElementById('part').style.color = "white";
document.getElementById('kli').style.color = "white";

if(document.getElementById)
document.getElementById(i).style.color = "blue";

return false;
}