function doLayer (aID) {
	var ie4 = ( document.all ) ? true : false;
	var ns4 = ( parseInt(navigator.appVersion) < 5 );
  var ns5 = ( parseInt(navigator.appVersion) > 4 );
  
  var state = '';
  closeAllLayers();
  
  if (ie4) {
    state = document.all[aID].style.visibility;
    if (state == 'hidden' || state == '') {
           document.all[aID].style.visibility = 'visible';
    } else {
           document.all[aID].style.visibility = 'hidden';
    }

  } else if(ns4) {
    state = document.layers[aID].visibility;
    (state == 'hide' || state == '')
          ? document.layers[aID].visibility = 'show'
          : document.layers[aID].visibility = 'hide';
          
  } else if (ns5) {
    state = document.getElementById(aID).style.visibility;
    (state == 'hidden' || state == '')
          ? document.getElementById(aID).style.visibility = 'visible'
          : document.getElementById(aID).style.visibility = 'hidden';
  }
}

function showLayer (aID) {
	var ie4 = ( document.all ) ? true : false;
	var ns4 = ( parseInt(navigator.appVersion) < 5 );
  var ns5 = ( parseInt(navigator.appVersion) > 4 );
  
 if (ie4) {
  document.all[aID].style.visibility = 'visible';
 } else if(ns4) {
  document.layers[aID].visibility = 'show';
 } else if (ns5) {
  document.getElementById(aID).style.visibility = 'visible';
 }
}


function closeAllLayers () {
	var ie4 = ( document.all ) ? true : false;
	var ns4 = ( parseInt(navigator.appVersion) < 5 );
  var ns5 = ( parseInt(navigator.appVersion) > 4 );
  
  if (ie4) {
    document.all['profil'].style.visibility = 'hidden';
    document.all['hydraulik'].style.visibility = 'hidden';
		document.all['maritim'].style.visibility = 'hidden';
	document.all['montagen'].style.visibility = 'hidden';
	document.all['stahlbau'].style.visibility = 'hidden';
	document.all['industrie'].style.visibility = 'hidden';
	document.all['kontakt'].style.visibility = 'hidden';
  } else if(ns4) {
    document.layers['profil'].visibility = 'hide';
	document.layers['hydraulik'].visibility = 'hide';
	document.layers['maritim'].visibility = 'hide';
	document.layers['montagen'].visibility = 'hide';
	document.layers['stahlbau'].visibility = 'hide';
	document.layers['industrie'].visibility = 'hide';
	document.layers['kontakt'].visibility = 'hide';
  } else if (ns5) {
    document.getElementById('profil').style.visibility = 'hidden';
	document.getElementById('hydraulik').style.visibility = 'hidden';
	document.getElementById('maritim').style.visibility = 'hidden';
	document.getElementById('montagen').style.visibility = 'hidden';
	document.getElementById('stahlbau').style.visibility = 'hidden';
	document.getElementById('industrie').style.visibility = 'hidden';
	document.getElementById('kontakt').style.visibility = 'hidden';
  }
}