// JavaScript Document
<!-- script language="JavaScript">
function sh(id) {
         for (i=1; i<=10; i++) {
              d = document.getElementById("t"+i);
              if (d)
              	d.style.visibility = 'hidden';
         }
         d = document.getElementById(id);
         d.style.visibility = 'visible';

         return null;
}
function h(id) {

         d = document.getElementById(id);
         if (d)
				 	d.style.visibility = 'hidden';
}

function subscribe_test(Form) {
  vstup = document.forms[Form].mail.value;
  mail=/^.+@.+\..{2,4}$/;
  if (mail.test(vstup)!=true) {
    document.forms[Form].mail.focus();
    return false;
  }
}

function unsubscribe_test(Form) {
  if(document.forms[Form].unsubscribe_check.checked == false) return false;
  vstup = document.forms[Form].mail.value;
  mail=/^.+@.+\..{2,4}$/;
  if (mail.test(vstup)!=true) {
    document.forms[Form].mail.focus();
    return false;
  }
}