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Well what did you do before you broke the site? When I accessed your site last time, it was normal. I scanned your site, and I didnt find anything wrong with the script files.

Edit: It seems to me that you messed up with the styles. I set the default theme to 'main' and 'green' and both are working(although the dropdown menu is broken, but that's another problem), while if I set the theme to be bookstore it will not work. So I wonder, did you modify some files in /css or /templates/bookstore folder? This may be the cause of your issue, but note that helping you with custom CSS is beyond my responsibility of support here.