I would carefully resize the browser windows because it became annoying very quickly (especially if the user opens the page directly, and not as a pop-up window). What if the user wants a little space around the content to make it easier to read? In most browsers, you can also disable some Javascript effects, such as moving and resizing windows - they can be disabled by default.
The icabod idea of wrapping content in a div should work fine, at least for height. If the width still shows the full width of the current window, try adding float:leftand it will match the width of the content.
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