diff --git a/demo/default.css b/demo/default.css
index 26249ddd..b5030189 100644
--- a/demo/default.css
+++ b/demo/default.css
@@ -55,6 +55,8 @@ textarea {
 .flex-fill {
   flex-grow: 1;
   flex-basis: 0;
+  min-width: 0;
+  min-height: 0;
 }
 .highlight {
   background: yellow;