* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

  body, html {
    height: 100%;
    font-family: Arial, sans-serif;
  }
 
  header {
    position: relative;
    width: 100vw;
    height: 100vh;
    background: url('photo/course.jpg') no-repeat center center;
    background-size: cover;
    filter:brightness(0.7);
    -webkit-filter:brightness(0.7);
}

  h1 {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 3rem;
    color: white;
    text-shadow: 2px 2px 8px rgba(0,0,0,0.7);
    text-align: center;
    width: 100%;
    
  }

  .btn-voir {
    position: absolute;
    top: calc(50% + 70px);
    left: 50%;
    transform: translateX(-50%);
    padding: 10px 20px;
    font-size: 1rem;
    background-color: #ffcc00;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    box-shadow: 2px 2px 6px rgba(0,0,0,0.3);
    text-decoration: none;
  }

  
  .btn-voir:hover {
    background-color: #ffdd33;
  }

  @media (max-width:768px) {
    h1{
        font-size: 2rem;
    }
    
  }