Faint gray dotted line

My site is currently offline because we are building it but I wanted to edit something and need your help. In every single section that is in black one is able to see a faint gray dotted line. For example between the header and the first block of content there’s a gray dotted line but the same is true with the body of the page. How do I go about removing the gray line so the sections flow continuosly. Thank you.