It's time to say something!
i use last fm every day and i'm scrobbling a lot of music.
so this extension i use for years now (changing red to middle blue), togehter with the user css syle from Gomgon on github (Stylus extension needed) makes a perfect readable and dark last fm site.
Thanks for sharing it with us!
Maybe you make an advanced version in the future combining dark style from Gomgon with your one?