Any way to change the font-size in chm files?

I just installed Windows 7 and since this, I can no longer change the font-size in existing chm files . Do you have any suggestions? I really want to change the font size of my chm files.
Any way to change the font-size in chm files?
I am using ChmZoomer. It is a great extension.

ChmZoomer gives you handy full page zoom functionality in all other browser-based applications, such as Chm files, e-Books, RSS Reader and so on.

http://www.goldgingko.com/chmzoomer

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