How small can I make the individual Cards in a V2 Deck?

Try setting min width to 1px and max width to Automatic

Unfortunately, that expands the card to a width of ~450px.

I’ve had good luck with setting the explicit minimum width you want. Like 126px. Also I keep the maximum set automatically - and it uses the contents of the card to set the max. If contents are less than the minimum, no max spread…

It seems that a null value on minimum width triggers the default - which as you know is 350px…

O. Kay.
Set the minimum width so the maximum width will be limited. Not at all logical, but surprisingly, it works!
@Skuidward_Tentacles was on the right track - but use a manual maximum, not automatic.

As it turns out, the manual maximum attribute is ignored unless the minimum is non-null. A space, or random text is fine. (I won’t call that a bug, but you may want to run it by the coders. 😉 )

Glad you got it sorted!