Size image on open only

[xp]

I have an html file that simply acts as a viewer for a document scanned as a
jpg.

Since the document is relatively high resolution, the image is huge. When
the html file is opened it sets the width of the image to 100% so the image
is resized nicely and fits on the page.

The problem is the browser won't let me resize the image after the file is
opened. When I change the zoom control (lower right corner) the image is
immediately resized again to 100%.

I want to open the file with the image initially set to 100% width, but I
need to be able to zoom it up if needed. How can I accomplish this using CSS
or HTML only?

My current code:

CSS:

#resize {width=100%;}

BODY:

<img src="myDoc.jpg" id="resize">

Thanks!