I made several different e-mail templates based upon the same structure and the same CSS. All look great on all devices, including iPhone 6 and iPhone 6+. However, the three-column version of my template has the dreaded right-side margin on iPhone 6s and up. The rest do not.

I have no idea what could be causing this, and I do not have the time available to try to recreate the issue in as few lines of code as possible. I am posting this in the hope that someone may have experienced this before and may know how to address it, or some kind and generous individual would want to look over my HTML files to spot the issue.

Here is a link to three screenshots as well as the HTML files for the same three e-mails on my GitHub.

Thank you. I appreciate any help I can get.