Modify Widths in Panel

1st post - take it easy on me! :slight_smile:

In the attached, you will see that I have a Box integration aside a Google Map integration. There is a good bit of unused space between the two and I would like to modify the HTML to make better use (by both of the aforementioned add-ins) of the space.

If I inspect element the “blank space”, I see that the field in question has a width value of 12.5%. If I “edit attribute” to 5% and an commit the change, I render a desirable result.

How do I change this in the source code?

Many thanks!