How to set max width of an image in CSS

Question

On my website I would like to display images uploaded by user in a new window with a specific size (width: 600px). The problem is that the images may be big. So

Answer 1

I see this hasn't been answered as final.

I see you have max-width as 100% and width as 600. Flip those.

A simple way also is:

I use this often, and then you can control individual images as well, and not have it on all img tags. You could CSS it also like below.

 .image600{
     width:100%;
     max-width:600px;
 }