[MM-61623][MM-61632][MM-61635] Remove min-width for the RHS when window size <400px (#31389)

Co-authored-by: yasserfaraazkhan <attitude3cena.yf@gmail.com>

webapp/channels/src/sass/layout/_sidebar-right.scss

@@ -27,6 +27,10 @@
             }
         }
 
+        @media screen and (max-width: 400px) {
+            min-width: unset;
+        }
+
         @media screen and (min-width: 901px) {
             min-width: 304px;
             max-width: 400px;