AQP, I'm not sure if this will work, but here's what I did:
.summary-item {
margin-top: -30px !important;
}
Deleting the rest of the code you wrote and using just what's above worked for me, both in the custom CSS window and after I saved.
(For what it's worth, I know very little about CSS, and in fact used your code to edit the spacing on my site. I tinkered with it until I arrived at only the code that made a difference.)
Hope that helps. Thanks again for posting your code.
EDIT: I did some more tinkering, because I wanted to shrink the margin at the bottom of the summary block, and here's what worked for me:
.sqs-block-summary-v2 {
margin-bottom: -40px !important;
}
I then consolidated the two, because why not (I don't know if this is how you're supposed to organize CSS, but it seemed logical) :
.sqs-block-summary-v2 {
.summary-item {
margin-top: -10px !important;
}
margin-bottom: -40px !important;
}
It still works in both the custom CSS window and after save. Again, hope that helps. đź‘Ť