I'd love to use this tool for wire-framing sites by creating them as an assembly of components, that means I'll be nesting a lot of cards.
Example here: app.infinitymaps.io/maps/4NRPb87j3B7#Website_Flow
If there is a mode to automatically stretch and collapse the cards to hug the content or stretch to the surrounding container, that'd make things super quick.
Bonus to automatically recognise and allow me to drag cards to a horizontal or vertical grid.
We have added some automatic growing of parent cards when you resize their children. Also directly adjacend cards resize their widths or heights together - does this already cover your need?