Hi Rob,
Thank you for reaching out to us. This usually happens when there is an invalid html code with orphaned or a missing a closing tag in the content, please check your page content and look out for a missing closing tag and close it.
The Cornerstone shows the content correctly due to it’s auto correct feature however the front-end breaks the layout due to invalid HTML markup.
If the issue persists then try clearing all caches (cache plugin, server cache and browser’s cache) and clear the style cache by navigating to Admin > Cornerstone > Status > Clear Style Cache
Also make sure that you are fully updated, as many bugs are fixed in the latest release. You can find the latest version numbers here: (http://theme.co/changelog/) Then you can compare them to what’s installed on your site.
If you find anything to be out of date, you can review our update guide.
If nothing works then please get back to us with the result of the steps above and URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.
All the best!