You can create a one-cell table and apply a background color to it.
More options, including how the manual does it, here: How to make a box like in the Scrivener User Manual - #22 by slothinker
You can create a one-cell table and apply a background color to it.
More options, including how the manual does it, here: How to make a box like in the Scrivener User Manual - #22 by slothinker