diff --git a/ext/greenwich/scss/_tweaks.scss b/ext/greenwich/scss/_tweaks.scss
index e472c7e5e416..9e1f4a9bf963 100644
--- a/ext/greenwich/scss/_tweaks.scss
+++ b/ext/greenwich/scss/_tweaks.scss
@@ -29,3 +29,9 @@ input[type="search"]::-webkit-search-cancel-button {
 summary {
   display: list-item;
 }
+/* Reset breaky stuff from some cms themes: https://lab.civicrm.org/dev/core/-/issues/5561 */
+#bootstrap-theme legend {
+  position: initial;
+  text-transform: inherit;
+  float: none;
+}