How do restrict the width of portfolio grid:simple so it's the same as the site width?

Portfolio Grid: Simple stretches beyond the site width. How do restrict it, so that it adheres to the width of the site? The only options I can see are "Full" and "Inset". Neither are suitable. Thanks

Hi,

Can you share link to portfolio grid page?

www.davidcliff.design

Current max width is 3000px to avoid the problem. 

19 hours ago, DavidCliff said:

www.davidcliff.design

Current max width is 3000px to avoid the problem. 

Add to Design > Custom CSS

div#gridThumbs {
    max-width: 900px;
}