Save this in a bookmarklet and click it to turn any website dark:

    javascript:(function(){const id='_dark_mode_bm';const el=document.getElementById(id);if(el){el.remove();}else{const s=document.createElement('style');s.id=id;s.textContent='html{filter:invert(1) hue-rotate(180deg)!important;background:#fff!important;}img,video,canvas,picture,svg{filter:invert(1) hue-rotate(180deg)!important;}';document.head.appendChild(s);}})();

    javascript:(function(){const id='_dark_perf_bm';const el=document.getElementById(id);if(el){el.remove();}else{const s=document.createElement('style');s.id=id;s.textContent=':root{color-scheme:dark!important;}html,body{background-color:#141414!important;color:#dcdcdc!important;}div,section,article,nav,header,footer,aside,main,table,tr,td,th,ul,ol,li{background-color:#18191a!important;color:#dcdcdc!important;border-color:#383838!important;}p,span,h1,h2,h3,h4,h5,h6,b,strong,i,em{color:inherit!important;}a,a%20*{color:#58a6ff!important;}pre,code,kbd{background-color:#202224!important;color:#ff9857!important;}input,textarea,select,button{background-color:#262626!important;color:#fff!important;border:1px%20solid%20#444!important;}img,video,canvas,picture{background-color:transparent!important;}';document.head.appendChild(s);}})();