Extend message tying of RHS threads the entire width of the right post textbox (#25857)

webapp/channels/src/sass/components/_post-right.scss

@@ -158,7 +158,7 @@
         .msg-typing {
             display: block;
             min-width: 1px;
-            max-width: 230px;
+            max-width: 100%;
             height: 20px;
             margin: 2px 0;
             float: left;