Custom 3-Panel Accordion

Card 1 body content.

When Card 1 and Card 2 are expanded, Card 3 is always collapsed. If you collapse Card 2 from this state, Card 1 grows to fill the space.

Card 2 body content.

Card 1 + Card 2 can be expanded at the same time, but then Card 3 must be collapsed.
Click Card 2 header in that state → collapse Card 2, Card 1 fills the space.
Click Card 2 header again (while Card 1 is expanded) → revert to the previous state.

Card 3 body content.

Clicking Card 3 header collapses Card 1, keeps Card 2 as-is, and expands Card 3 from the bottom.