diff --git a/core/css.ts b/core/css.ts
index 5a44cc0b6..20c573093 100644
--- a/core/css.ts
+++ b/core/css.ts
@@ -307,6 +307,7 @@ let content = `
 .blocklyMinimalBody {
   margin: 0;
   padding: 0;
+  height: 100%;
 }
 
 .blocklyHtmlInput {