chore(css): add two types of attribute values for overflow

[LockingReal]

/**
 * Specifies what to do with contents that overflow the available space for the panel. Possible values:
 * "squish" - Children are squished to fit within the panel's bounds if needed (default)
 * "clip" - Children maintain their desired size but their contents are clipped
 * "scroll" - Children maintain their desired size and a scrollbar is added to this panel
 *
 * Examples:
 * overflow: squish squish; // squishes contents in horizontal and vertical directions
 * overflow: squish scroll; // scrolls contents in the Y direction

*/ 🦋❤️🥰

[LockingReal]

Hello classmate @Perryvw , I have looked at the recent merge request list and you have join review these requests recently. Can you help me take a look at the real scenes from our project 😉