Centering the last picture ("Multiple sets") of the project grid

Site URL: https://pike-begonia-fjck.squarespace.com/

Hello, 

on the page of "classes"  i would like to align to centre the last image of the project grid (called "Multiple sets") so that it looks like a row of 2, another row of 2 and last row of just 1. what code should i insert?

https://pike-begonia-fjck.squarespace.com/

password: hello123

Thank you 

12 hours ago, gypseagiuls said:

Site URL: https://pike-begonia-fjck.squarespace.com/

Hello, 

on the page of "classes"  i would like to align to centre the last image of the project grid (called "Multiple sets") so that it looks like a row of 2, another row of 2 and last row of just 1. what code should i insert?

 

https://pike-begonia-fjck.squarespace.com/

password: hello123

 

Thank you 

 

try

#gridThumbs {
  grid-template-columns: repeat(4,minmax(0,1fr));
}
#gridThumbs .grid-item:last-child:nth-child(2n - 1) {
  grid-column-end: -2;
}
#gridThumbs .grid-item {
  grid-column: span 2;
}

where should i put this?  i did portfolio settings - advanced - insert code but it doesn't change to me. 

Just now, gypseagiuls said:

where should i put this?  i did portfolio settings - advanced - insert code but it doesn't change to me. 

Can you try in custom css section

great it worked - thanks so much