diff --git a/static/css/theme.css b/static/css/theme.css
index d48bad54d0..5d9f8ccf38 100644
--- a/static/css/theme.css
+++ b/static/css/theme.css
@@ -412,17 +412,18 @@ th {
     margin-top: -1rem;
 }
 
+#body .flex-block-wrapper {
+    margin-left: auto;
+    margin-right: auto;
+}
 /* we limit width if we have large screens */
 @media screen and ( min-width: 1300px ){ /* #sidebar/width + ./max-width */
-    #body #body-inner {
-        margin: auto;
+    #body .flex-block-wrapper {
         max-width: 1000px;
     }
 }
 
 #body-inner.chapter {
-    margin-left: auto;
-    margin-right: auto;
     padding: 2rem 9rem;
 }
 @media only all and (max-width: 59.938em) {