Looks like both -webkit-animation and -webkit-transition are deprecated.
What's the modern standard for things like a CSS fade-out?
You can't deprecate something that was never part of the standard.
Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
Vendor prefixes allow you to use experimental features before they are part of the standard (if ever). What you probably want to do is use just animation and transition which are part of the CSS standard now.