Allow trailing whitespace

postcode_lookup/templates/index.html

@@ -28,7 +28,7 @@ <h1 class="c-hero__title">
                                     id="postcode-search"
                                     type="text"
                                     name="postcode-search"
-                                    pattern="^([A-Za-z]{1,2}[0-9][A-Za-z0-9]? ?[0-9][A-Za-z]{2}|GIR ?0AA)$"
+                                    pattern="^([A-Za-z]{1,2}[0-9][A-Za-z0-9]? ?[0-9][A-Za-z]{2}|GIR ?0AA) ?$"
                                     required>
 
                             <button type="submit" name="Submit Postcode"