Seersucker says what?

The picture you posted looks good to me. The stripe color on the shorts is faint anyway, so anything goes.

I would recommend to never try to match colors unless they are sold together. The colors will never actually quit match and will look off. Just go with something that's obviously a different color. That could also mean the same color, just a way darker or lighter shade of that color.

Your fit looks good here.

The color saturation of the seersucker is really low and it reads as nearly white. So you've got a lot of leeway when picking colors. I would just steer away from near matching colors and patterns.

To me, colors that almost but don't quite match are the worst. A real pet peeve that drives me nuts.