This doesn't seem too far off from ~80 characters per line, which I believe is best practice for readability. Though you could make the column wider and bump up the font size and it would be even more readable.

Have you ever seen a book?

They have huge gutters and margins, and not-quite-black text on creme/off-white/never-actually-white backgrounds... why? Because it's easier of the eyes for long blocks of text.

This page isn't a long block of text. Look at what Reader View does to pages. It doesn't ADD gutters and margins, it shrinks them.

Depends on the width of the browser window. Wide margins that are welcome in a full-page browser on a large or ultrawide display are cancer when I'm tiling windows 2 or 3 up on a smaller or narrower display.

Ah, thank you. The next version of the page will include a YUUUGE sitemap on the left and the table of contents on the right.

We'll also add a wonderful floating text input box to let you chat with our helpful AI assistant.