Adjust padding on block in Squarespace

[NVC]

I have a blog page with a Sidebar.

In the sidebar I have an text block and under that is a social Links block.

I want to reduced the space between them.

So questions are:

1. Should I add code to the CSS page or to the Blog page in the Advanced area?

2.  If I reduce the padding at the bottom of the text block would this be correct?

sidebar-one-content {
id=yui_3_17_2_1_1573151273605_9004
padding: bottom 0px;
}

Thank you!