I take a minimalistic approach, which is not perfect, but good enough for me, and gets my preferred font size and dark mode support. CSS:

:root { color-scheme: light dark; }

* { background-color: revert !important; color: revert !important; font-size: revert !important; }

center { text-align: left !important; }

table#hnmain { width: 100% !important; }