We are looking into adding this in control in Layout and Design section. However, in the mean time, you will need to change this through Customizer.
Please go to Appearance >> Customize >> Custom CSS and JS >> Custom CSS box and add the code below:
.feature-block {
background: #c02127;
}
And if you would like to remove the vertical separators as well, please add this code just below the code you added in first step.
.feature-block li:before {
display: none;
}
Thank you