CSS Padding around masonry grid gallery help

Site URL: https://sandralynnallendesign.squarespace.com/living

CSS Padding around masonry grid gallery help please:

I'm used to being able to adjust the width of a section - the rest of the site's sections are set to "Medium" and line up with the outer edges of the logo and navigation bar as the red lines in the screen grab attached indicate. Is there a way to adjust the padding on this masonry gallery section to be medium width to match the rest of the site?  I feel like it should be obvious but I can't seem to adjust the width of this gallery. 

https://sandralynnallendesign.squarespace.com/living

Pass: 1234

Thanks so much!  

You can't adjust section width?

10 hours ago, tuanphan said:

You can't adjust section width?

For some reason, no, do you know what the issue might be? OK if not. 

https://sandralynnallendesign.squarespace.com/living

Password: 1234

Thank you! 

On 6/1/2020 at 2:22 AM, CarolynSmith said:

 

For some reason, no, do you know what the issue might be? OK if not. 

https://sandralynnallendesign.squarespace.com/living

Password: 1234

Thank you! 

Hi. You can adjust Site Content Width. Access Home > Design > Site Styles > Spacing > Site Spacing > Page Width