Hi Angela,
There is something funny going on here. On the page you linked to, there is the correct gch-header div within the site-content div. This is the one generated by the plugin. But then there is a second one right before the closing body tag (i.e. </body>). This is what it looks like, I pulled this from the inspector:
<div class="gch-header" style="background: url(https://www.structuralbuildings.com/wp-content/uploads/2015/10/SB-HEADER_3.jpg ) !important;
background-size: cover !important;
background-repeat: no-repeat !important;
background-position: top left !important;
width: 100%;
min-height: 400px;"></div>
Was this code added manually somehow? I don’t see how this could have been generated by the plugin for a couple reasons. First, the plugin cannot hook content into this location. And second, this div does not have the markup of the plugin. The general markup looks like this:
<div class="gch-header">
<div class="gch-header-inner ">
<div class="gch-header-image">
<div class="gch-header-image-inner"> ....more code....</div>
</div>
</div>
</div>