Need help turning this gray line into a black line

In a previous thread you helped me remove certain things and push my three feature areas up to be flush with the slider. There is a gray line that is left over. Can I change this gray line to black so that it matches? I have included an image, so that you can see what I am talking about. Thank you.

 

Hi,

Please use the css code given below.

Code:

.content-container {
border-top: 6px solid black;
}

Thanks,
Praveen