Ligatures in monospace fonts hurt legibility of config keys

[rybak]

The choice of the font in app/assets/stylesheets/variables.scss for the rule:

$fixed-width-font-family: Courier, monospace;

can make it harder to read some of the text in the documentation. This is especially applicable to the names of the configuration keys and to mentions of the shell commands, which people would usually edit in a text editor or in a shell with a monospace font. Fonts used by <code> tags are also affected.

URL for broken page

Example: https://git-scm.com/docs/git-config

Problem

Ligatures in the fonts for the Courier in CSS make it harder to read parts of the website.

Operating system and browser

Operating System: KDE neon 5.27 (≈ Kubuntu 22.04)
Browser: Firefox 119.0

Steps to reproduce

1. Look at mentions of reflog in monospace font on page https://git-scm.com/docs/git-config#Documentation/git-config.txt-gcreflogExpireUnreachable
   

Other details

• Adding CSS code:

  font-variant-ligatures: none;

  fixes the instances highlighted on the screenshot above:
  
• Other examples:
  • mention of color.diff.new
  • mention of git config
    
    These styled via <code>.
• MDN documentation for font-variant-ligatures
• In my setup, these CSS rules for Courier actually end up using Nimbus Mono PS. This is caused by config file /etc/fonts/conf.avail/30-metric-aliases.conf, quote:

       <alias binding="same">
         <family>Nimbus Mono PS</family>
         <default>
         <family>Courier</family>
         </default>
       </alias>

  See also Arch Linux wiki article about it.

[sparr]

ArtifexSoftware/urw-base35-fonts#31

font-variant-ligatures: none; seems like a good fix, until various monospace fonts stop shipping this sort of ligature