lucy24 - 1:58 am on Jul 23, 2011 (gmt 0)

If I change the width to something else (like 100px), the image sizes doesn't change for some reason. Am I doing something wrong here?

No, your browser is doing something right. Images are displayed at actual size unless the <img> declaration itself gives a different size. It can be expressed either in pixels (should always be the real size) or in percentages. That means percentage of the containing box, not percentage of the image's real size. But then you have to perform further jiggery-pokery to make sure the image never comes out larger than its real size-- which is very rarely successful unless it's some kind of decorative blur.

If you want to display images at something other than their actual size in pixels, proceed with extreme caution. Among other things, you're forcing the user to download a larger image than they'll be seeing, and you're relying upon the browser to resize gracefully, which is not always the case.