diff --git a/lms/static/sass/discussion/elements/_navigation.scss b/lms/static/sass/discussion/elements/_navigation.scss
index 76b33427e9..1eb002911d 100644
--- a/lms/static/sass/discussion/elements/_navigation.scss
+++ b/lms/static/sass/discussion/elements/_navigation.scss
@@ -17,6 +17,7 @@
   @include box-sizing(border-box);
   display: table;
   border-bottom: 1px solid $gray-l2;
+  width: 100%;
   background-color: $gray-l3;
 }
 
diff --git a/lms/static/sass/discussion/views/_thread.scss b/lms/static/sass/discussion/views/_thread.scss
index 71a7da7a41..4106cf1378 100644
--- a/lms/static/sass/discussion/views/_thread.scss
+++ b/lms/static/sass/discussion/views/_thread.scss
@@ -32,6 +32,10 @@ body.discussion, .discussion-module {
       @extend %t-weight5;
     }
 
+    .posted-details .username {
+      font-size: inherit;
+    }
+
     .response-header-content {
       display: inline-block;
       vertical-align: top;