From 6dd6b448485f99d99b2cfb24d516c56135611945 Mon Sep 17 00:00:00 2001
From: Stuart Taylor <staylor1012@gmail.com>
Date: Wed, 11 Apr 2018 14:43:54 +0100
Subject: [PATCH] Fix firefox css tests

---
 .../learn/src/templates/Challenges/components/preview.css    | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/learn/src/templates/Challenges/components/preview.css b/packages/learn/src/templates/Challenges/components/preview.css
index 74e98b86f9..9baf72764b 100644
--- a/packages/learn/src/templates/Challenges/components/preview.css
+++ b/packages/learn/src/templates/Challenges/components/preview.css
@@ -1,5 +1,8 @@
 .hide-test-frame {
-  display: none;
+  position: absolute;
+  top: -9999px;
+  left: -9999px;
+  visibility: hidden;
 }
 
 .challenge-preview, .challenge-preview-frame {