Styling to make cards in entity rows fit better & remove padding

[twhittock]

I'm not sure this is a real feature request or just documenting what I found. I searched in the issues in this repo to see how to remove padding for a card, and couldn't find anything. Here's how I ended up adding an entity row in HA 2022.10 without a box shadow or excessive padding:

  - type: custom:hui-history-graph-card
    entities:
      - entity: switch.central_heating_pump_zones_downstairs
    hours_to_show: 12
    card_mod:
      style: |
        ha-card {
          box-shadow: none;
        }
        div.content {
          padding: 0px;
        }

I guess it'd be nice to have that as a trick in the tests folder?