Greg,
Which sidebar widget are you using for the “Series” section in the sidebar? Could you change the “Series” to be a custom menu widget instead?
The markup for the “Series” widget is different from a custom menu so the styles may not be 100% accurate, but this custom CSS should work:
.widget_seriestoc li {
border-top: 1px solid rgba(255, 255, 255, 0.2);
padding: 8px 0 9px;
}
.widget_seriestoc li:first-child {
border-top: 0;
}
.widget_seriestoc li ul {
border-top: 1px solid rgba(255, 255, 255, 0.2);
margin-top: 9px;
}
.widget_seriestoc li li:last-child {
padding-bottom: 0;
}
.content-sidebar .widget_seriestoc li {
border-color: rgba(0, 0, 0, 0.1);
}