function center(pageHeight,pageWidth,layerName,layerWidth,layerHeight){

if(layerHeight==0){topLimit=0;}else{

  if((pageHeight-layerHeight)>0){
    topLimit=Math.abs(Math.round((pageHeight-layerHeight)/2));
  }else{
    topLimit=5;
  }

}

if(layerWidth==0){leftLimit=0;}else{

  if((pageWidth-layerWidth)>0){
    leftLimit=Math.abs(Math.round((pageWidth-layerWidth)/2));
  }else{
    leftLimit=5;
  }

}

  locate(layerName,topLimit,leftLimit,0,0);

}


function locate(layer,topLimit,leftLimit,marginTop,marginLeft){

	document.getElementById(layer).style.top=topLimit+marginTop+'px';
	document.getElementById(layer).style.left=leftLimit+marginLeft+'px';
}