Getting more specific about darkmode styling

[chocopie]

Hi, I hope it's okay to open this pull request. The original styling wasn't working properly for me, and I made a few rushed hacks to stave off a headache 😅 These changes are to get more specific about darkmode styles (black/grey backgrounds and orange for links), and also dimming images. I'm not a super confident coder, and I'm sorry in advance if these tweaks are crap!