Nope. Didn't change anything at all. Just loaded the forum up, opened a category, and there it was. I'm displaying the screen in "Dark Mode", which is a quick toggle from the menu in the upper right. But I've been doing that since day one (it's easier on these old eyes). It affects no other website that I've visited, even other forums using the same software. Y'all understand that it's the column spacing, not the color, that is the issue, right?
The reason I use portrait mode is that it's too uncomfortable to reach the center of the screen when typing in landscape mode.
Samsung Galaxy Tab A 10.1". Mine always has a keyboard across the bottom, too (at least when typing is an option). In portrait mode, it's fine. In landscape mode, if you're holding it in your hands (which I almost always do), it's a very long reach to the center of the screen with the thumbs.