A section isn't complete without paddings and margins, and the new HubSpot page editor offers the option to customize them.
In each section's Alignment and Spacing option, you'll find:

1. Content Alignment
- Content Center:
Set a custom container's size that overwrites the theme's default container.
- Full Width:
Removes the section's container.
2. Padding and Margin

Customize each section's padding-top, left, right, bottom and margin-top, left, right, bottom.
The value set is applied to all screen sizes. Currently, there is no option to specify a custom value for mobile or desktop only.