@Tuanphan,
This is great—but the "row" part of your selector didn't work for me. Instead, I had to use "div":
I'm using 7.0 — maybe that's the difference?
#your-spacer-block-id + div {
your css code
}
As a note—I can never seem to get the right block I'D without using this browser extension: Squarespace ID Finder
I put the spacer directly above the row I wanted (it's important to check the "Elements" in your browser inspector to make sure it's correctly placed before (above) the row you want to select.