diff --git a/src/simulator.css b/src/simulator.css
index 09ed1a7..1d21954 100644
--- a/src/simulator.css
+++ b/src/simulator.css
@@ -31,6 +31,8 @@ div.container {
   width: 100%;
   padding: 0 3px 3px 3px;
   overflow: hidden;
+  background-color: white;
+  border-radius: 0.375rem;
 }
 
 label {