whooo…
You will get any sort of opinion here, and a lot of “it’s not a sin to wear X and Y…”
there is no definite acceptable criterias, as it depend on culture, time and place.
But well, there is no chance I will said you that tennis skirts are modest for a Catholic girl.
it’s obvious that modest with something so short is an oxymoron.
I would add I only wear ankle lenght skirt. Well, no, I have also only one dress that are at middle calf, but I wear it with tights or leggins in the winter.
Black tights versus naked legs can make a difference in what can be considered as modest too.