function getURLParam(strParamName){
  var strReturn = "";
  var strHref = window.location.href;
  if ( strHref.indexOf("?") > -1 ){
    var strQueryString = strHref.substr(strHref.indexOf("?")).toLowerCase();
    var aQueryString = strQueryString.split("&");
    for ( var iParam = 0; iParam < aQueryString.length; iParam++ ){
      if ( aQueryString[iParam].indexOf(strParamName + "=") > -1 ){
        var aParam = aQueryString[iParam].split("=");
        strReturn = aParam[1];
        break;
      }
    }
  }
  return strReturn;
} 

var site = getURLParam("site");
var site_id;

switch(site){
	default:
	case "home":
		site_id = 1;
	break;
	case "company":
		site_id = 2;
	break;
	case "services":
		site_id = 3;
	break;
	case "references":
		site_id = 4;
	break;
	case "contact":
		site_id = 5;
	break;
	case "impressum":
		site_id = 6;
	break;
}

function btn_set(){
	document.images["btn_"+site_id].src = "images/btn_"+site_id+"_act.gif";
}

function btn_over(target){
	var get_id = target.slice(4,5);
	if(site_id != get_id){
		document.images[target].src = "images/"+target+"_over.gif";
	}
}
function btn_out(target){
	var get_id = target.slice(4,5);
	if(site_id != get_id){
		document.images[target].src = "images/"+target+".gif";
	}
}
function btn_click(target){
	var get_id = target.slice(4,5);
	if(site_id != get_id){
		document.images[target].src = "images/btn_"+get_id+"_act.gif";
		document.images["btn_"+site_id].src = "images/btn_"+site_id+".gif";
		site_id = get_id;
	}
}