diff --git a/lib/form/templates/element-url.mustache b/lib/form/templates/element-url.mustache
index e161c8f8c2f..a7d1cde483a 100644
--- a/lib/form/templates/element-url.mustache
+++ b/lib/form/templates/element-url.mustache
@@ -1,7 +1,44 @@
+{{!
+    This file is part of Moodle - http://moodle.org/
+
+    Moodle is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Moodle is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+}}
+{{!
+    @template core_form/element-url
+
+    URL form element template.
+
+    Example context (json):
+    {
+        "element": {
+            "name": "test",
+            "id": "test0",
+            "wrapperid": "test0-wrapper",
+            "size": null,
+            "error": null,
+            "value": "http://example.org",
+            "frozen": false,
+            "iderror": "test0_error",
+            "attributes": "",
+            "filepickerclientid": "test0-filepickerclientid"
+        }
+    }
+}}
 {{< core_form/element-template }}
     {{$element}}
         {{#element.filepickerclientid}}
-            <div id="url-wrapper-{{element.filepickerclientid}}" class="d-inline-block">
+            <div id="url-wrapper-{{element.filepickerclientid}}" class="d-inline-block mw-100">
         {{/element.filepickerclientid}}
         <input type="url"
                 class="form-control {{#error}}is-invalid{{/error}}"