I fail to see the problem with this page, the large header is just announcing the topic, scrolling down there is no more distraction.

To me, the semi-transparent header and border are absolutely unacceptable. Imagine opening a book and 20% of the page are decor, decor with text no less. In clear words: this fucks with my attention, and the reason is that this is design that serves no actual purpose. If you're building a house or a product, anything that's not necessary is detrimental to the users experience, I don't even understand what can be argued about this

> Imagine opening a book and 20% of the page are decor, decor with text no less.

Regularly happens in "book world". Chapter headings are often an entire page, and sometimes even a double spread. The average whitespace around headings on the three closest books at hand were all 1/3rd of the page, making that decor even greater than the 20% you're describing.

House of Leaves is a book like this and the story is not the same without it. The words move down the page in a staircase fashion as Will Navidson is walking down the stairs to his untimely demise, in one example.

And reader view also works fine on Firefox, no clue what the OP is talking about.

Reader view has custom implementations per browser, in Safari the images are not loading.

Maybe you are running javascript blocking? I do too and I only get a white text on black background thanks to Dark Reader inverting the colors.