--- wp-admin.css (latest)
+++ wp-admin.css (working copy)
@@ -3607,6 +3607,10 @@
 	padding: 8px 0;
 }
 
+.form-wrap .form-field #parent {
+	max-width: 100%;
+}
+
 .col-wrap h3 {
 	margin: 12px 0;
 	font-size: 1.1em;