message: docs(theming): add card css variable for dark mode
diff: @@ -258,6 +258,8 @@ body.dark {
  --ion-toolbar-background: #0d0d0d;
  --ion-item-background: #000000;
  +
  + --ion-card-background: #1c1c1d;
  }
  @@ -300,5 +302,7 @@ body.dark {
  --ion-toolbar-background: #1f1f1f;
  --ion-tab-bar-background: #1f1f1f;
  +
  + --ion-card-background: #1e1e1e;
  }
  ```
  