diff --git a/components/sandbox/index.js b/components/sandbox/index.js
index 840bbaa94f7210..c5841deab992a8 100644
--- a/components/sandbox/index.js
+++ b/components/sandbox/index.js
@@ -142,6 +142,9 @@ class Sandbox extends Component {
 				width: 100%;
 				height: 100%;
 			}
+			body > div > iframe {
+				width: 100%;
+			}
 			body > div > * {
 				margin-top: 0 !important;	/* has to have !important to override inline styles */
 				margin-bottom: 0 !important;