Vier: Border between side menu and content in "flat" style

view/theme/vier/flat.css

@@ -2,3 +2,13 @@
 body, section { background-color: #ffffff !important;}
 #profile-jot-form { background-color: #ffffff !important;}
 .dspr, .twit, .pump, .dfrn { background-color: #ffffff !important;}
+
+div.pager, ul.tabs {
+  box-shadow: unset;
+  background-color: unset;
+  border-bottom: unset;
+}
+
+aside {
+  border-right: 1px solid #D2D2D2;
+}