function showContent(content_div){
	document.getElementById('content_welcome').style.display = "none";
	document.getElementById('content_about').style.display = "none";
	document.getElementById('content_Contact').style.display = "none";
	document.getElementById('content_MetalScrapTrade').style.display = "none";
	document.getElementById('content_Production').style.display = "none";
	document.getElementById('content_Transport').style.display = "none";
	document.getElementById('content_LoadingService').style.display = "none";
	document.getElementById('content_RecyclingOfVehicles').style.display = "none";
	document.getElementById('content_RecyclingOfElectro').style.display = "none";
	document.getElementById('content_certificate').style.display = "none";
	
document.getElementById(content_div).style.display = "block";

	/*
$(content_div).show('slow');
*/
}