.site-content .post has `overflow: hidden;`, .site-content .entry-content has `max-width: 965px;`, and .wide-content has `margin-right: -34.0740%;` Disabling the margin-right or, preferably, the max-width rule will fix the layout. Or make your browser less than 1700px wide.
(Crazy rats nest of CSS rules, I assume this is a wordpress/wordpress template thing.)
Ahh, just saw this after posting my comment. Yes, it appears that at 1700px or greater it cuts off text. Shown in this video: https://cs.joshstrange.com/BB60xzBW
I've seen a number of websites that don't like being in windowed mode on desktop, and the very occasional website that doesn't like my tablet (which has a custom width/dp size set). I always assumed they were related to media queries that were set incorrectly, as zooming or resisting the window (or on my tablet, toggling desktop view) nearly always fixes it.
Then there's the websites that have a menubar or other UI floating on top of the content it takes you to (this is far more common, and incredibly frustrating as I'm usually using either a toc or a search function and unable to see the content I'm looking for at all)