Safari is using an away-from-zero rounding strategy to cast number values assigned to an integer property.

Chrome uses the "nearest" strategy that JS's Math.round() uses.
"nearest" is also the default rounding for the round() CSS function

Here is a reduced test case showing the differences:

https://codepen.io/propjockey/pen/vYvMbaX/253c4756c72e962cb10b0c19b396ea37?editors=1100

Thank you!
// Jane