The light mode is fine, but you're right the dark mode is truly awful, the code blocks are unreadable.

edit: for some reason the author overrode the background color on code blocks via an inline style of

    background-color:#f0f0f0

from

    var(--code-background-color) = #f2f2f2

to make the background nigh imperceptibly darker, but then while the stylesheet properly switches the to #01242e in dark mode the inline override stays and blows it to bit.

Not that it's amazing if you remove the inline stle, on account of operators and method names being styled pretty dark (#666 and #4070a0).