The overflow shorthand will accept two values making it possible to set overflow-x and overflow-y to different values. If two values are specified, the first is overflow-x and the second is overflow-y. This property previously only accepted one value, meaning that a developer who wanted to set them to different values was forced to write longhand statements for both. Changing the shorthand reduces complexity by allowing developers to specify both in a single statement.
Docs: https://developer.mozilla.org/en-US/docs/Web/CSS/overflow https://github.com/w3c/csswg-drafts/issues/2484