<!DOCTYPE html>
<html>
    <head>
        <script>
            window.onload = function() {
              document.body.offsetWidth;
              document.body.style.top = "100px";
            };
        </script>
    </head>
    <body><div style="position: relative; top: inherit"><div style="position: absolute; top: inherit">This text should be 200px from the top of the body</div></div></body>
</html>