No implicit widening conversions ...

... between integral and floating point types.
As "diffs that would make you leave the party" go that has to be up way up there. Replace magic numbers 48 and 96 with 7 and 35. And... voila!

It's an encoding of the weak conformance relation. If B % A == 0 then A weak_<:< B. In the case of Float, all the integral types were factors of 48, and afterward none of them are factors of 7. Could have been 5.