How to create borders round?

Site URL: http://testofpurity.com/

I've found some code that generates a field of color for my testimonials, but I want the edges to be rounded. Am I to suppose that more modifying of the code is required to make this happen? If so, what exactly would this be?

Add to Design > Custom CSS

#kt-layout-id_5c36f2-9b > .kt-row-column-wrap {
    border-radius: 20px !important;
}