From https://drafts.csswg.org/css-scrollbars/#scrollbar-color-properties,
Applies to: block containers and boxes that establish a formatting context [same as elements that overflow applies to]
However, they are not the same. overflow does not apply to
- Inline formatting context roots.
overflow makes the block container establish a BFC instead, and an anonymous IFC root without overflow is generated.
- Ruby formatting context roots. They are inline-like boxes, so
overflow does not apply.
- Table formatting context roots.
overflow is used on the table wrapper box instead of on the table box.
So I would just say
Applies to: [same as elements that overflow applies to]