Workaround for card-specific css is using card id, eg to change the background color of the card header for card 123 named "important card" you'd add this to "*css":
.cardid-123 .card-header {
background: #507
}
Workaround for now is using cardtype's style name, eg to change the background color of card headers of Organizations, you'd add this to "*css": .type-Organization .card-header { } Note however that the CSS style will always be the original name of that cardtype card. Inspect the HTML of any card of the type in question to see it's original name.
background: #507
|cardname|+*self+*css
|cardtype|+*type+*css
etc.
setting-ize css+discussed in support tickets
setting-ize css+relevant user stories