In fact, 64-bit Mac will be the only version supported as of Firefox 53. This wi...

cpeterso on Dec 15, 2016 | parent | context | favorite | on: Firefox Hardware Report for Web Developers

In fact, 64-bit Mac will be the only version supported as of Firefox 53. This will halve the Mac installer size. 32-bit and Universal Mac builds were dropped in Firefox bug 1295375: https://bugzil.la/1295375