Invisible border in the group of text blocks.

Problem/Motivation

When I set the theme to Secondary and enable the grid, the border on the right and bottom is almost invisible.

Steps to reproduce

• Add a "group of text blocks" paragraph.
• Add two items that contain an image and some text.
• In the Settings tab, enable the "Enable grid" option.
• Save.
• Now you can verify that the border at the bottom and on the right is almost invisible.