Margin:

The set margin is marked in red in the template work area. The white area is available for the positioning of the elements.

If you want to make sure that elements do not extend into the margin, then please regard, that the setting of the X/Y coordinates (Elements dialog area) considers the margin.

Example: The blue rectangle considers the margin and completely fills out the available width of the work area.

Nudge: Hereby you can adjust the offset of the marked element per click with an arrow key (smaller offset).

Nudge + SHIFT: Hereby you can adjust the offset of the marked element per click with an arrow key (bigger offset).

Unit: A fixed unit "mm" is already set.