I'm just checking in very quickly, but Nextgen might give you the option - I just tried with mine on www.clipartillustrations.com, and it does not scale. Let me know if you find an option!

I made the theme in general pretty responsive, but most designers will likely be shopping from behind a computer - not necessarily a device or handheld. If you require scalability there are probably more modern options like the ones people are using on their sites.

Any suggestions people?