Hello Paul,
Thanks for submitting a question about the mobile responsiveness of your blog posts. It seems there are a few lines of CSS padding and margin control affecting this content area:
padding-right: 5em;
padding-left: 5em;
margin-right: 100px;
margin-left: 100px;
Without these, the content displays nicely on mobile. I can only guess that these were added to the theme, because this is the first time I’ve seen that kind of behavior in a page layout.
Best,
Christopher M.