Fixing Angular 21 by migrating all values by signals. (#11)

frontend/src/app/app.component.scss

@@ -1,14 +1,14 @@
 :host {
-    display: flex;
-    flex-direction: column;
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+
+  app-header {
+    width: 100%;
+  }
+
+  main {
     flex: 1;
-
-    app-header {
-        width: 100%;
-    }
-
-    main {
-        flex: 1;
-        padding: 1em 0;
-    }
-}
+    padding: 1em 0;
+  }
+}