I have a yellow border line at the bottom of my header

I have a yellow border line at the bottom of my header section that I can't seem to get rid of. I have gone into the region css and the only thing there showed:
.upfront-region-container-bg {
border-bottom: 1px solid #c09533;
color: #fffff;
}

When I try deleting the css and/or changing the color it doesn't do anything that I can see. I need the bottom to be either transparent or black but I definitely don't need a yellow line there.