I'm 55 years old. My eyes are not what they used to be and neither are my glasses. I also own a copy of "Usage and Abusage" but I'll pass on that. Click on story link. My laptop renders a page - OK its black text on a white background (thank you but I doubt its a deliberate boon) ...
... why on earth is the offering a "page" ie emulating a printed page? In portrait!
I'll accept that most people are not fixated about grammar, punctuation or basic decency: that's fine.
However a "page" in portrait that looks awful on a landscape screen is unpleasant. You can easily request my viewing parameters and adjust accordingly. It's even worse when you are dispensing advice about www page layouts.
I’ll accept that not everyone likes a portrait page on a landscape screen, that’s a matter of taste. But if you’re going to invoke Usage and Abusage, grammar, punctuation, and "basic decency", it would help to identify an actual error. And perhaps write "it’s" correctly while doing so. I’m also unclear what moral failing you think an A4 aspect ratio represents.
Longer lines of text are harder to read. There's a reason newspapers, books, articles, etc are all vertical and often have a similar amount of words per line. It's easier to follow, scan, and find your place.
Some more on this below:
Optimal Line Length in Reading — A Literature Review (https://journals.uc.edu/index.php/vl/article/view/5765)
Practical Typography — Line Length (https://practicaltypography.com/line-length.html)