Add the ability to set background color & border on sections

Request: Add the ability set a custom background color and border to content sections (ie. the Markdown card).

Other than using custom HTML, the only way to have a background to a section is by using the Callout card.

Use Case: This would be especially useful for newsletters, as it allows sections to be separated more clearly. In email newsletters, it is common to have sponsored sections use a different background color, and/or a border, but there’s not currently a way to do this in Ghost without custom HTML.

The ability to group sections/cards would also help with this, as you could add a border to the section. See how Beehiiv does this for an example.