Index: src/wp-admin/css/media.css
===================================================================
--- src/wp-admin/css/media.css	(revision 47290)
+++ src/wp-admin/css/media.css	(working copy)
@@ -852,6 +852,8 @@
 .wp_attachment_holder .imgedit-wrap .imgedit-panel-content {
 	float: left;
 	padding: 3px 16px 0 0;
+	min-width: 400px;
+	max-width: calc( 100% - 266px );
 }
 
 .wp_attachment_holder .imgedit-wrap .imgedit-settings {
@@ -1207,6 +1209,7 @@
 	.wp_attachment_holder .imgedit-wrap .imgedit-settings {
 		float: none;
 		width: auto;
+		max-width: none;
 	}
 }