Board Thread:General Discussion/@comment-30671736-20151118200538/@comment-5811199-20151118204647

.comments li[data-user="Aethelhelm"] blockquote { background:#FFFF66 !important; }

.comments li[data-user="Aethelhelm"] blockquote:after { border-color:transparent #FFFF66 #FFFF66 transparent !important; }

.comments li[data-user="Aethelhelm"] blockquote div { background:transparent !important; } Change  into a colour of your choice.