We already replied on your question on TF in comments section but we`ll re-paste this answer here as well.
This is how it supposed to be what you can see on http://themes.muffingroup.com/betheme/blog We designed it like that. But if you don`t like those lines, please use below css:
Comments
This is how it supposed to be what you can see on http://themes.muffingroup.com/betheme/blog
.widget:after { border: none; }