I have a long HTML5 help document with a table of contents at the top. When the page is scrolled and the table is no longer visible, I want to display a floating div containing a link to the table:

```
<div id="DivTableOfContentsLink">
    <a href="#TableOfContents">
        Table of Contents
    </a>
</div>

```

Is it possible to achieve this sing CSS only (without JavaScript)?