This comes from the breadcrumbs styling.
Apparently, checking Hide breadcrumbs does not remove their container, so if it is styled, you still see a remaining piece.
@weaver, is there a reason that when people select “Hide breadcrumbs”, their empty container remains in the page HTML?
@leswaldeck in the mean time you can do one of two things.
Add the rule below in Main Options > FOnts & Custom > Custom CSS Rule box.
#breadcrumbs {display:none;}
or check if you see the rule below in that same box, and remove it.
#breadcrumbs {background-color:#29598C;color: #FFF;padding: 2px 4px;border-radius: 3px;}