feat: Use Aura

There is no class with @NpmPackage yet so it is added manually for now

Author: Artur-

src/main/frontend/themes/my-theme/styles.css renamed to src/main/frontend/styles.css

@@ -1,8 +1,4 @@
-/*
-   CSS styling examples for the Vaadin app.
-
-   Visit https://vaadin.com/docs/styling/application-theme/ for more information.
-*/
+@import '@vaadin/aura/aura.css';
 
 /* Example: CSS class name to center align the content . */
 .centered-content {

src/main/frontend/themes/my-theme/theme.json

@@ -1,11 +1,13 @@
 package org.vaadin.example;
 
-import com.vaadin.flow.component.page.AppShellConfigurator;
-import com.vaadin.flow.server.PWA;
-import com.vaadin.flow.theme.Theme;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
+import com.vaadin.flow.component.dependency.CssImport;
+import com.vaadin.flow.component.dependency.NpmPackage;
+import com.vaadin.flow.component.page.AppShellConfigurator;
+import com.vaadin.flow.server.PWA;
+
 /**
  * The entry point of the Spring Boot application.
  *
@@ -15,7 +17,7 @@
  */
 @SpringBootApplication
 @PWA(name = "Project Base for Vaadin with Spring", shortName = "Project Base")
-@Theme("my-theme")
+@CssImport("./styles.css")
 public class Application implements AppShellConfigurator {
 
     public static void main(String[] args) {