stylesheet ignored in Circumference Lite

Currently I am using Circumference Lite on a fresh WordPress installation and I wanted to make the site tighter by using the following command in the stylesheet:

#cir-wrapper-boxed-medium {
    max-width: 980px;
}

Problem is, the change is being ignored. Tried both on the main theme and the child theme. I have made this change on another site of mine and this worked. Also tried making changes on the Twenty Fifteen theme but these are not ignored. What can I do?