Really cool. Browsing HN at night was painful on my Macbook. It's a shame we need an extension for this, a few CSS lines could fix this while keeping the website small.

By the way, I think some of your CSS rules need to be fixed. Contrasts between elements for example. When looking at comments, the username has a foreground of #828282 and the background is #161618. That's a 4.7:1 ratio. You pass the AA level but not the AAA level, which requires a 7:1 ratio for small texts: https://webaim.org/resources/contrastchecker/?fcolor=828282&...