function moveDIV( var1) {
    	if ( var1 == 0 ) {
    		document.getElementById("nav_content").style.left = "0px";
    		document.getElementById("nav_content").style.top = "0px";
    	} else {
    		var2 = document.getElementById("nav_content").style.top;
    		var2 = Number(var2.substring(0, var2.length-2)) + var1;
    		var3 = document.getElementById("nav_content").offsetHeight;
    		var4 = document.getElementById("nav_container").style.height;
    		var4 = Number(var4.substring(0, var4.length-2)) - var3;
    		if ( var2 <= 0 ) {
    		      if ( var2 >= var4 ) {
    			document.getElementById("nav_content").style.top = var2 + "px";
    		      } else {					
    			document.getElementById("nav_content").style.top = var4 + "px";
    		      }
    		} else {
    			document.getElementById("nav_content").style.top = "0px";
    		}
    	}
    }
     
    function wheel(event){
     wheeldiv = this.id;
      var delta = 0;
      if (!event) event = window.event;
      if (event.wheelDelta) {
       delta = event.wheelDelta/120;
       if (window.opera) delta = -delta;
      } else if (event.detail) {
       delta = -event.detail/3;
      }
      if (aktiv) window.clearInterval(aktiv); 
      if (delta > 0) moveDIV(20);
      if (delta < 0) moveDIV(-20);
      return false;
    }
     
    function scrollwheel(){
      document.getElementById('nav').onmousewheel = wheel;
      if (window.addEventListener) {
      document.getElementById('nav').addEventListener('DOMMouseScroll', wheel, false);
      }
     
    }
     
    function fadeDIV( var1 ) {
    	document.getElementById('steuerung').style.opacity = var1 / 10;
    	document.getElementById('steuerung').style.filter = 'alpha(opacity=' + var1*10 + ')';
    }
     
    function init() {
    	aktiv = "";
    	document.getElementById("nav_container").style.overflow = "hidden";
    }
     
    if ( window.addEventListener ) {
    	addEventListener( "load", init, false );
    } else {
    	attachEvent( "onload", init );
    }