--- a/devtools/client/themes/webconsole.css
+++ b/devtools/client/themes/webconsole.css
@@ -1128,18 +1128,18 @@ a.learn-more-link.webconsole-learn-more-
   flex: 1;
   direction: ltr;
   overflow: auto;
   -moz-user-select: text;
   position: relative;
 }
 
 html,
-body,
-#app-wrapper {
+body {
+  display: block !important; /* Until Bug 1409413 removes the accidental display: flex */
   height: 100%;
   margin: 0;
   padding: 0;
 }
 
 body {
   overflow: hidden;
 }