Some strange bug in Siblime Text 3, why does .logo:hover work like this, but .logo::hover doesn't?

Question

css

For some reason, in siblime Text 3, this code works:

.logo:hover {
  opacity: .6;
}

but there is no such:

.logo::hover {
  opacity: .6;
}

What is the problem I can not understand ... Who can come across?