Added Sass compiler and correct indenting.

src/App.vue

@@ -1,6 +1,6 @@
 <template>
-  <img alt="Vue logo" src="./assets/logo.png">
-  <HelloWorld msg="Welcome to Your Vue.js + TypeScript App"/>
+    <img alt="Vue logo" src="./assets/logo.png" />
+    <HelloWorld msg="Welcome to Your Vue.js + TypeScript App" />
 </template>
 
 <script lang="ts">
@@ -8,20 +8,13 @@ import { defineComponent } from 'vue';
 import HelloWorld from './components/HelloWorld.vue';
 
 export default defineComponent({
-  name: 'App',
-  components: {
-    HelloWorld
-  }
+    name: 'App',
+    components: {
+        HelloWorld
+    }
 });
 </script>
 
-<style>
-#app {
-  font-family: Avenir, Helvetica, Arial, sans-serif;
-  -webkit-font-smoothing: antialiased;
-  -moz-osx-font-smoothing: grayscale;
-  text-align: center;
-  color: #2c3e50;
-  margin-top: 60px;
-}
+<style lang="scss">
+    @import "@/sass/main.scss";
 </style>