fix(submit): keep page width stable when dialogs open

assets/css/frontend/pages/submit.css

@@ -1,4 +1,9 @@
 /* Front-end article editor — follows the reference theme's newposts page. */
+/* Keep the layout width fixed when a submission dialog locks page scrolling. */
+html:has(> body.jio-page-submit) {
+  scrollbar-gutter: stable;
+}
+
 /* The form wraps both float columns; flow-root keeps it from collapsing. */
 #jio-submit-form {
   display: flow-root;