Make the toolbar fixed to the top; tweak contents

Add a comment count (which links to the full discussion) and show the reply button normally on mobile.

extensions/embed/less/forum/extension.less

@@ -14,12 +14,24 @@
   border-top: 0;
 }
 .DiscussionPage-nav--embed {
+  height: 70px;
+
   > ul {
-    padding: 0;
+    z-index: 100;
+    background: @body-bg;
     list-style: none;
+    padding: 0;
     margin: 0;
     border-bottom: 1px solid @control-bg;
 
+    @media @tablet-up {
+      position: fixed;
+      left: 0;
+      right: 0;
+      top: 0;
+      padding: 0 15px;
+    }
+
     > li {
       margin: 15px 15px 15px 0;
       display: inline-block;
@@ -29,6 +41,14 @@
         right: auto;
       }
     }
+    .item-replies h3 {
+      font-weight: normal;
+      margin: 0;
+
+      &, a {
+        color: @muted-color;
+      }
+    }
   }
 }
 .DiscussionPage-stream {