What is the Outer Area background on the Layout tab, and why doesn't it colour my section?

Outer Area colours the band around the section, not the section itself. That band is the room you create with Space, plus the space at the sides when the section has a custom width.

With no Space set, the band has no size, so the Outer Area colour is hidden behind the section and nothing seems to change.

• To colour the section itself: open the Style tab and use Background Type (the note under Outer Area links straight there).
• To use Outer Area: first set Space, for example Above and Below to M. Then pick a Background Colour or Background Image under Outer Area.

Click Save when done.