R Markdown change backround color of sections in CSS

I was wondering if its possible to change the background color of an rmarkdown based flexdashboard with css.

In particular, I have a document structure like this:

---
  title: "Test"
output: 
  flexdashboard::flex_dashboard:
  vertical_layout: scroll
logo: logo.jpg
self_contained: no
---
  Overview {data-orientation=rows data-icon="ion-ios-home"}
=====================================  

  Row
-------------------------------------
  ### Plot 1

  ### Plot 2

  Row
-------------------------------------

  ### Plot 3

  ### Plot 4

What I want to do is change the background color of the sections that are seperated by the Row layout.

For example, one section would be gray, the following one white.

Is this possible, and if yes, any hints how I could do it?