.center-content {
  display: flex;
  justify-content: center;
  align-items: center;
}
.pied-de-page{background-size: cover}
body { background-image: 
     url(https://cdn.eu.yapla.com/company/CPYOJAnYsioRwTjKltBveIqdL/asset/images/Arri%C3%A8re%20plan%20flout%C3%A9%20bis.png) ;
     background-size: cover ;
     background-attachment: fixed;
     background-repeat: no-repeat;}