CSS as static resource.

src/app.css

@@ -0,0 +1,11 @@
+window { 
+  background: black;
+  font-size: 30px;
+}
+label {
+  background-color: #fff;
+  border: 2px solid gray;
+  border-radius: 5px;
+  margin: 10px;
+  padding: 10px;
+}