How to improve difference-in-differences graph? I want to visualise what basically is a difference in difference graph but in a better way. My first idea was two split violin plots and it looks good but is too complex for the reader.

Any ideas on what to use or how to make this look decent?
Here the data




Group
Profit Round 2
Profit Round 3




Treatment
198.4205
291.0428


Control
266.7899
311.5257




I can tell that the treatment group starts out lower than the control group and, while the treatment group winds up lower than the control group, the treatment group has closed the gap. For difference-in-differences, this is exactly what I would want to see.
One possible improvement is to put standard errors on the four point estimates. Maybe more useful than that would be to plot the differences between control and treatment groups along with the standard errors of the differences.
If you just want to look fancy, bright colors tend to do the trick, though they will convey no additional information.
