Hi Hasibul,
That sounds unpleasant. For one, I can’t choose any one page (or subset of pages) to hide the div on – downloads are linked from most pages in the website. For two, it would be fairly easy for this code to affect other parts of the theming since “.w3eden” is not a unique css selector to the download manager’s template wrapper. And #3, it means that the page will flash as the layout is reworked.
Is this wrapper added by download manager? if so, it would be nice to make that optional. If it is added by wordpress, then … well ok.