/* ž ¹öÆ° */
var isDOM = (document.getElementById ? true : false);
var isIE4 = ((document.all && !isDOM) ? true : false);
var isNS4 = (document.layers ? true : false);
var isNS = navigator.appName == "Netscape";

function getRef(id) { 
	if (isDOM) return document.getElementById(id); 
	if (isIE4) return document.all[id]; 
	if (isNS4) return document.layers[id]; 
} 

function moveRightEdge()
{ 
	go_top = getRef("btn_top");
	
	var yMenuFrom, yMenuTo, yOffset, timeoutNextCheck; 
	if (isNS4) { 
		yMenuFrom   = go_top.top; 
		yMenuTo     = window.pageYOffset + 500;   // À§ÂÊ À§Ä¡ 
	} else if (isDOM) { 
		yMenuFrom   = parseInt (go_top.style.top, 10); 
		yMenuTo     = (isNS ? window.pageYOffset : document.body.scrollTop) + 500; // À§ÂÊ À§Ä¡ 
	} 

	timeoutNextCheck = 500; 

	if (yMenuFrom != yMenuTo) { 
		yOffset = Math.ceil(Math.abs(yMenuTo - yMenuFrom) / 20); 
		if (yMenuTo < yMenuFrom) {
			yOffset = -yOffset; 
		}
		if (isNS4) {
			go_top.top += yOffset;
		} else if (isDOM) {
			if ((document.body.scrollHeight - 500) <= parseInt(go_top.style.top, 10) && yOffset > 0) {
				go_top.style.top = parseInt(go_top.style.top, 10) + "px";
			} else {
				go_top.style.top = parseInt(go_top.style.top, 10) + yOffset + "px";
			}
			timeoutNextCheck = 10;
		}
	} 
	setTimeout ("moveRightEdge()", timeoutNextCheck); 
}

if (isNS4) {
	var go_top = document["btn_top"];
	go_top.top = top.pageYOffset + 630;
	go_top.visibility = "visible";
	moveRightEdge();
} else if (isDOM) {
	var go_top = getRef('btn_top');
	go_top.style.top = (isNS ? window.pageYOffset : document.body.scrollTop) + 630 + "px";
	go_top.style.visibility = "visible";
	moveRightEdge();
}

function f_moveTop(){
 if (isNS4) { 
  window.pageYOffset = 0;
 } else if (isDOM) { 
   document.body.scrollTop = 0;
 } 
}