Extra margin for a block of text

One scene of my book includes the text of a letter. I decided to format the letter using a slightly larger left and right margin around its text, but don’t see how to accomplish that in Scrivener.

How can I do that while preserving maximum compatibility when compiling my manuscript? I’m on Windows.

I don’t have the Windows version so haven’t tested this. Until someone with experience chimes in––search in the Manual for “Block-Quoting” and “Preserve Formatting”.

Good Luck.