I accidentally pressed a lot of keys on my keyboard and for some reason the default colors of Firefox have changed. I found out that by using Ctrl+Alt+D that I can switch the colors back to normal or to the colors that now appear automatically, but this only works for one tab. If I open a new tab, it shows the weird colors (see images below). I tried looking up specific shortcuts for Firefox considering the shortcut mentioned before (Ctrl+Alt+D) only works on Firefox. But I can't find any shortcut tied to that combination. I'm unsure what to do and how to fix this.

I would appreciate it if someone could tell me how to fix this.