Hmmm... do you know what version you have?

It should work on iOS 11.3 and up... maybe. They might have smaller limits on the number of operations per calc()..? Can't think of anything overtly incompatible.

Unfortunately Safari is today's IE6 in web dev since they're so far behind on so many features. Except it's worse since you can't test without owning their products or paying for a service either... wish I could check it out, there's probably something to learn