Tailor adds three layout settings to the Customizer which mirror those in the Tailor sidebar:
1. Section width. The default maximum width for sections across the entire site.
2. Column spacing. The default amount of spacing between columns (i.e., gutter width).
3. Element spacing. The default amount of vertical spacing between elements (aka. vertical rhythm).
You can enter any unit type you like, for example 100%, 400px or 5em.
Layout settings are applied in this order:
1. Site layout settings from the Customizer.
2. Page layout settings from the Tailor sidebar.
3. Element layout settings from the Edit dialog.