How do you remove section padding from Brine

Hi. I'm a newbie to Squarespace, but have done my share of HTML, CSS, ASP, WordPress, Hubspot, etc. My site is a hot mess right now and I have lots of questions, but for now, this is the biggest problem I can't solve. I can not for the life of me figure out how to remove padding in between sections on the Brine template. 

https://dodecahedron-chartreuse-yr7h.squarespace.com/
123M45)(*

TIA!

You can add this to Design > Custom CSS

/* remove Index Section Padding */
div.Index-page-content {
    padding-top: 1px;
    padding-bottom: 1px;
}