Dark mode looks fine to me: light gray on black.

Light mode is terrible: dark gray on black.

You get light grey? The headings are #101828 and body text #364153 on #0a0a0a for me.

Light mode text: oklch(37.3% .034 259.733)

Dark mode text: oklch(87.2% .01 258.338)

Background in both modes: oklch(14.5% 0 0)

See here: https://jsfiddle.net/kmtwf4g3/

I think the fuckup of the website author is that the background is black instead of white in light mode. Otherwise the text colors would be fine as they are. Probably vibe coded and never tested in light mode.

Light gray on black is not fine. Background should not be black, the text blurs.

I'm in a daylit room on a laptop screen in dark mode. Some of the text was literally invisible. If the site's owner is reading this, you should fix that.