I think this is a twin-flagged jumping spider. Found this cutie on rusted train tracks.
This spider was about 2-3mm in size.
It was also jumping when I was photographing it. Found another fuzzy image on my drive of this one. On its abdomen, black, dark brown with white colored spots around the margin and one larger one in the center. It’s absolutely a twin-flagged if someone wants to update the ident.
Hi.certainly looks like you pegged it, no doubt a juvenile,i often spot them at 4 MM.
Nice photo! Jumpers are my favorite!