Set maximum width to 40rem across screen sizes

[McSinyx]

Referencing GH-45: 50% is really narrow on smaller screen sizes, the maximum width should instead be calculated from the font size.

Some rules are removed to correct the bounding box size
in browser inspector and fix the overflow on the x-axis.

The now-unused div.parent is removed; please hide whitespace changes when view the diff for better clarity.

[httpjamesm]

Hmm... On smaller windows I'm seeing overflowing on the X axis on the homepage.

On mobile devices, the answer pages lack padding.

And on large devices (this is an extreme example), this version is actually narrower than the current version.

vs

[McSinyx]

On smaller windows I'm seeing overflowing on the X axis on the homepage.

Oops, sorry, I forgot to check the home page. The style sheets are unified now.

On mobile devices, the answer pages lack padding.

Silly me, I switched to CSS variable last minute and didn't realize var doesn't work for media queries. Padding should be restored now.

And on large devices (9000x5918), this version is actually narrower than the current version.

This is expected. Re GH-45: readability is improved by shortening the line length in characters. I switched to 40rem for backward compatibility with the old home page's width, also to roughly accommodate the standard 80-column terminal output.

People with high-res display would usually enable HiDPI or adjust the font size so it should not be an issue in practice.

[httpjamesm]

There are still issues. The homepage is no longer vertically centered, probably due to the removal of the parent div.

[McSinyx]

You are right, and I am horribly sorry I didn't check that. The home page is vertically centered now.

Edit: huh wait, I removed body { display: flex } before to fix text wrapping when screen got narrower than around 420px. Not sure why it broke in the original style, lemme investigate a bit further. Edit: NVM GH-113 would lower that down below any realistic screen width.

[McSinyx]

The original stylesheet's issue where it's impossible to scroll to the top of a vertically overflowed home page is also fixed now.