fix

Author: rachelandrew

transitions/js-transitions.html

@@ -18,7 +18,12 @@
         }
 
         main {
+            display: flex;
+            justify-content: center;
+            align-items: center;
             max-width: 960px;
+            height: 400px;
+            border: 1px solid #ccc;
             margin: 0 auto;
             padding: 20px;
         }