Merge pull request #13425 from edx/bjacobel/topic-list-corners

Fix extremely minor box corner issue in Discussions

lms/static/sass/discussion/elements/_navigation.scss

@@ -154,6 +154,7 @@
     padding-left: 0;
     overflow-y: scroll;
     list-style: none;
+    border-radius: 0 0 3px 3px;
 
     .forum-nav-thread-labels {
         margin: 5px 0 0;