Originally, we have this CSS definition by Bootstrap: webkit-transition: -webkit-transform .6s ease-in-out. PostCSS creates this CSS definition: transition: transform 0.6s ease-in-out, -webkit-transform 0.6s ease-in-out;.

When we break the new definition down in separate parts, we have this: transition: -webkit-transform 0.6s ease-in-out;

So we basically get another definition as is already defined by Bootstrap, probably necessary for some mobile Safari stuff, so I'm fine with this change.