alt Hacker NewsCourier New is a bad font that no one should choose to use. In typical font-weight terms, where Regular should be 400, it’s 200–250, because it was improperly digitised, not taking ink bleed into account. Windows put some hacks into ClearType to make it render a little less badly, but they’re not dependable these days.
(“Courier”, as provided by macOS, is fine. But Courier New is irredeemably bad.)
Concerning font-family declarations, if you’re doing something like `"Courier New", Courier, monospace`—please just write `monospace`.
(I’m not going to address the font size.)
It renders terribly on sizes below ~14px, even on a Retina display. No anti-aliasing setting can save it.
A modern typeface like IBM Plex Mono [1] or Office Code Pro [2] that offers more weights and can still render nicely at 10px size would be a better choice, maintaining the same aesthetic.
[1] https://fonts.google.com/specimen/IBM+Plex+Mono
[2] https://open-foundry.com/fonts/office-code-pro