Feature Content Background

See top of https://rmofcanwood.ca/ Can you advise on the CSS to reduce the width of the white background (Featured Content) to content-width instead of the full width. I can't reduce the opacity, have it not display, OR change the color of the Feature Content background since the length of each of the 4 entries is different and they also have a white background, and there is no secondary background that contains them which I was hoping. The best option is to reduce the width unless you can advise another way.   Thanks Glen