Make the left sidebar in Discussion page accessible

TNL-5169

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

@@ -55,6 +55,22 @@
     width: 100%;
 }
 
+.forum-nav-browse-menu-following {
+    .icon {
+        @include float(left);
+        @include left($baseline / 2);
+        position: relative;
+        top: 13px;
+    }
+    .forum-nav-browse-title {
+        @include padding-left($baseline * 1.5);
+    }
+}
+
+.forum-nav-browse-menu-item {
+  margin-bottom: 0;
+}
+
 .forum-nav-browse-title {
     @include text-align(left);
     display: block;
@@ -66,10 +82,11 @@
     background: transparent;
     box-shadow: none;
     background-image: none;
-    color: $link-color;
+    cursor: pointer;
 
     &:hover,
-    &:focus {
+    &:focus,
+    &.is-focused {
         // switched from a to button;
         // need to override button styles
         background-image: none !important;

lms/static/sass/discussion/utilities/_shame.scss

@@ -21,11 +21,6 @@
 // navigation - browse menu
 // ------------------------
 
-// Override global a rules
-.forum-nav-browse-title {
-  color: inherit !important;
-}
-
 // Override global label rules
 .forum-nav-browse-filter label {
   margin-bottom: 0;