function on_obec(a)
{
 a.src="images/button2_obec.gif";
 document.getElementById("index_obec_content").style.visibility = "visible";
}

function off_obec(a)
{
 a.src="images/button1.gif";
 document.getElementById("index_obec_content").style.visibility = "hidden";
}

function on_ou(a)
{
 a.src="images/button2_ou.gif";
 document.getElementById("index_ou_content").style.visibility = "visible";
}

function off_ou(a)
{
 a.src="images/button1.gif";
 document.getElementById("index_ou_content").style.visibility = "hidden";
}

function on_info(a)
{
 a.src="images/button2_info.gif";
 document.getElementById("index_info_content").style.visibility = "visible";
}

function off_info(a)
{
 a.src="images/button1.gif";
 document.getElementById("index_info_content").style.visibility = "hidden";
}