We checked your webiste in Firefox and seems that we can’t get the same issue as you described, can you please share the screenshots on your end? On our local machines, your webiste looks good on the Browsers – Safari, Chrome, Mozilla FF, Opera.
I found the solution thanks. I’d installed the Hummingbird plugin and the cache settings were preveting the posts from appearing, except when I was logged in. This is why I could see then in Chrome (where i was logged in) but not in firefox (where i wasnt logged in).
Once Id turned off all the caching options, it worked fine.