1. Basic properties
visible (default value) the excess still showed normal
After hide hidden beyond
scroll scroll bars consistently show
adaptive auto show or hide scrollbars
inherit
overflow = overflow-x + overflow-y
If the overflow-x overflow-y values different
Wherein a is visible and the other is hidden scroll auto, then the first will be visible to auto reset
2. Scroll bars from non-html body
3.padding-bottom missing
4. The internal floating no effect
5.margin penetrating questions