check sass compilation

app/assets/app.js

@@ -6,7 +6,7 @@
  */
 
 // any CSS you import will output into a single css file (app.css in this case)
-import './styles/app.css';
+import './styles/app.scss';
 
 // start the Stimulus application
 import './stimulus/bootstrap';

app/assets/styles/app.css

@@ -1,3 +0,0 @@
-body {
-    background-color: lightgray;
-}

app/assets/styles/app.scss

@@ -0,0 +1,9 @@
+body {
+    background-color: lightgray;
+    padding: 5em;
+    div#boum {
+      background-color: white;
+      padding: 1em;
+      border: 1px solid grey;
+   }
+}