The issue with white contour lines displayed on the front actor

Hello everyone, I have encountered a small problem.
I created two actors, half cylinder A and vector arrow B, with half cylinder A at the back. When I set the transparency of A to be relatively small, about 0.16 (full transparency is 1), I saw white outline lines appearing on some arrows in front of B. I tried using
But it doesn’t work, the white outline still appears.
I want to solve the problem with this white contour line, as it appears particularly prominent on another computer.
Thank you for any suggestions and responses.

I have turned on anti aliasing and it looks very effective. It seems to have solved this problem.