类似于商品局部预览特效的JS问题求助

我也不知道怎么搞的  貌似火狐不兼容，ie内核的浏览器就都没问题
地址在这里：http://www.npc1860.tk/jieqi/image.html
代码：
<html>
<title>FF显示有问题</title>
<script language="JavaScript">
var srcX = 1024; //原图大小,可以任意设置
var srcY = 768;
var bigX = 300; //预览窗大小,可以任意设置
var bigY = 225;
var smallX = 300; //缩略图宽度
var smallY = srcY * smallX / srcX;
var viewX = bigX / srcX * smallX; //预览范围
var viewY = bigY / srcY * smallY;
var bl = srcX / smallX;//缩小比例
var border = 1; //边框
window.onload=function (){
        head.innerHTML="JS+CSS实现图片放大预览效果,鼠标可以滑动图片任意地方";
        smallpic.width=smallX;
        smallpic.height=smallY;
        bigpic.width=srcX;
        bigpic.height=srcY;
        view.style.width=viewX;
        view.style.height=viewY;
        smallbox.style.borderWidth=border;
        bigbox.style.borderWidth=border;
        if (window.event){
                smallbox.style.width=smallpic.offsetWidth+border*2;
                smallbox.style.height=smallpic.offsetHeight+border*2;
                bigbox.style.width=bigX+border*2;
                bigbox.style.height=bigY+border*2;
        }else{
                smallbox.style.width=smallpic.offsetWidth;
                smallbox.style.height=smallpic.offsetHeight;
                bigbox.style.width=bigX;
                bigbox.style.height=bigY;
        }
        move(event);
}
function move(e){
        var e = window.event?window.event:e;
        var iebug = 0;
        if (window.event){
                var vX = e.offsetX - viewX/2;
                var vY = e.offsetY - viewY/2;
        }else{
                var vX = e.pageX - viewX/2 - smallbox.offsetLeft - border;
                var vY = e.pageY - viewY/2 - smallbox.offsetTop - border;
                iebug = 2;
        }
        if (vX < 0) vX = 0;
        if (vY < 0) vY = 0;
        if (vX > smallX - viewX - iebug) vX = smallX - viewX - iebug;
        if (vY > smallY - viewY - iebug) vY = smallY - viewY - iebug;
        bigpico.style.marginLeft = - vX * bl 
        bigpico.style.marginTop = - vY * bl 
        view.style.left = vX + smallbox.offsetLeft + border;
        view.style.top = vY + smallbox.offsetTop + border;
}
</script>
<style type="text/css">
*{padding:0;margin:0}
img{display:block;}
#smallbox{border:1px #c33 solid;float:left;width:0;height:0;overflow:hidden}
#bigbox{border:1px #c33 solid;width:0px;height:0px;float:left;overflow:hidden}
#view{border:1px #ddd solid;width:0px;height:0px;position:absolute}
#head{text-align:center;line-height:40px;font:bold 16px/40px;color:red}
</style>
<div id="head"></div>
<div id="smallbox"><img src="4.jpg" name="smallpic" width="300" height="300" border="0" id="smallpic" onmousemove="move(event)" onmouseover="document.getElementById('bigbox').style.display='';document.getElementById('view').style.display=''" onmouseout="document.getElementById('bigbox').style.display='none';document.getElementById('view').style.display='none'"></div><div id="bigbox"  style="display:none"><div id="bigpico"><img src="4.jpg" name="bigpic" width="300" height="300" border="0" id="bigpic"></div>
</div>
<div id="view" onmousemove="move(event) "style="display:none"></div>