Here’s a quick tip for adding a dividing line between the Extra Theme sidebar and it’s content.

To do so, you can simply add the following CSS in the custom CSS box (Extra > Theme Options > General Settings > Custom CSS):

@media only screen and (min-width: 1025px) {
    div.et_pb_extra_column_sidebar { border-left: 1px solid #ccc !important; }

NB: Just change #ccc to the HTML color code of your choice.