Twenty-fourteen featured content border color

I am trying to change the color scheme in twenty-fourteen on itake5.com for the home page featured content. I have changed background color etc. but cannot get the right and left borders to change from black to #f5f5f5. I am using a child-theme and have found where to change it using Firebug. It will change in Firebug on the fly but when I put it into the child-theme style.css it does not change. I even use !important.

Here is the code in the child-theme.

.grid .featured-content .entry-header {
    height: 0px;
    border-left-color-value: #f5f5f5 !important;
    border-right-color-value: #f5f5f5 !important;
}

Thanks for the advice.