始终位于一个div的右上角

<body>body</body>
<script>
var obj=document.createElement('div');
obj.style.position="absolute";
obj.style.left=100;
obj.style.top=53;
obj.style.width=200;
obj.style.height=200;
obj.style.border="solid 1px black";
document.body.appendChild(obj);
var x = document.createElement("div");
x.style.width="12px";
x.style.height="20px";
x.style.styleFloat = "right";
x.innerHTML = "X";
obj.appendChild(x);
</script>