The font site is 9pt. It's just small. Not sure where someone got 12px from. The measurement is resolution independent, yes.

9pt == 12px on the web. You can check that in Web Inspector in computed styles.

Alternatively:

  1px = (1/96)in
  1pt = (1/72)in = (1/72)*(96/72)*(72/96)in = (96/72)*(1/96)in = (4/3)*1px = (4/3)px
  9pt = 9*1pt = 9*(4/3)px = 12px

https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Values_...

2560x1440 and ~12px on HN looks incredibly small.

I just switched the resolution to 1024x768, and now the same ~12px is "larger" and easier to read without needing to increase my browser zoom.

There's an obvious visual difference between the two.

Without HiDPI (sic!) scaling that means that a correctly-sized display for that resolution would have a 30" diagonal on Windows (standard PPI: 96) and 40" on Mac (standard PPI: 72). If you don’t have HiDPI (sic!) scaling enabled in your system and your display is smaller than that, then you’re basically browsing everything zoomed out.

Then your setup is not compliant with web standards. Most likely you need to enable DPI scaling somewhere.

I always need to zoom 125-130% on all sites on top of 125% desktop system zoom and HN needs no special treatment. E.g. wikipedia is basically the same.

Anyway, you can set [default] zoom once and enjoy.

Unless you’re in a browser in which no one uses that per-site zoom feature cause it’s not implemented cause no one uses it. In this case, you can embrace the simplicity or use StyleBot.