Under Settings > Website Settings > Website > Custom Header HTML add:

<style type="text/css">
.bnl-layout-1-00 a, .bnl-layout-2-00 a 
{ background: none!important; } 
.bnl-layout-1-00 a:hover, .bnl-layout-2-00 a:hover 
{ background: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0.8) 100%, rgba(0, 0, 0, 0.8) 100%) repeat scroll 0 0!important; } 
.bnl-layout-1-00 a span, .bnl-layout-2-00 a span 
{ background: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0.35) 5%, rgba(0, 0, 0, 0.8) 100%) repeat scroll 0 0 rgba(0, 0, 0, 0); } 
.bnl-layout-1-00 a:hover span, .bnl-layout-2-00 a:hover span 
{ background: none; } 
</style>