this screenshot was actually taken before the color changes, but nowadays you can do this
download scratch addons from https://scratchaddons.com/ → turn on “website dark mode and customizable colors” and “editor dark mode and customizable colors” → turn on the preset “scratch’s default colors (blue)”
you’re welcome :) just a heads up in case you haven’t used scratch addons or any scratch browser extensions before, you’re not allowed to advertise or name browser extensions or userscripts on scratch. that goes against a policy they added a while back which disallows that.
i presume you meant to say “disallowed”. you can find out more on the official announcement topic: https://scratch.mit.edu/discuss/topic/284272/?page=1#post-2907564