final version I guess

src/App.css

@@ -36,3 +36,10 @@
     transform: rotate(360deg);
   }
 }
+
+.titre {
+  background-color : lightblue;
+  border-radius: 1em;
+  padding: 2em;
+  margin: 1em;
+}

src/App.js

@@ -10,11 +10,7 @@ const App = () => {
   return (
     <div>
       <div className="App">
-          <div style={{
-              background:   'lightblue',
-              borderRadius: '1em',
-              padding:      '2em',
-              margin:       '1em'}}>
+          <div className="titre">
             <h1>Bienvenue sur notre super site !</h1>
           </div>
       </div>

src/App.test.js

-import { render, screen } from '@testing-library/react';
-import App from './App';
-
-test('renders learn react link', () => {
-  render(<App />);
-  const linkElement = screen.getByText(/learn react/i);
-  expect(linkElement).toBeInTheDocument();
-});

src/Counter.js

@@ -2,7 +2,6 @@ import { useState } from "react";
 
 const Counter = (props) => {
     const [count, setCount] = useState(0);
-    console.log(props);
     return (
         <div class="card" style={{width:"auto", margin: '2em'}}>
             <div class="card-header">