At this site I have an error using the parent theme's
jquery.PrettyPhoto.js This causes tabs not to load well nor gallery to work well it seems. The error states
TypeError: $.browser is undefined http://www.domain.com/wp-content/themes/decondo/lib/scripts/pretty/jquery.prettyPhoto.js?ver=2.5 Line 59
I enqueued jQuery Migrate - v1.0.0 - 2013-01-14 with following code (whole function added): http://pastebin.com/EC3XrTiq
to the parent theme's function.php as I thought it would be related to an outdated jQuery function - see https://stackoverflow.com/questions/14524289/browser-is-undefined-error -.
I found another thread at SE that suggested adding the $.browser function mentioning this function was no longer used since 1.3. The version loaded on those pages is 1.8.3 so this could be the issue then. Odd I did not have the issue earlier, but anyways.
I realized that jQuery migrate was not being loaded checking these pages in Firebug. I is located here for sure though and would say the path is correct.
Thanks to to some more research and a check in safari using the inspector I did realise the jQuery migrate scripts is already loaded by WordPress.
Now the issue remains why the site's gallery (issues in Safari with layout), menu (dropdown broken in Firefox) and tabs (not loaded in Firefox) are not loading well and if the deprecated browser function is causing this or not.