.header {
	background: #A5A4A4;


}
.footer {
  grid-column: 1 / -1;
  background: #A5A4A4;
 position: absolute;
  width: 100%; height: 50px;
  bottom: 0; left: 0; right: 0;
}

.navigation-list {
  display: grid;
  gap: .5rem;
  /*background: #FF7C00;*/
}

/* Bonus : Centré ? */
// .website {max-width: 800px; margin: 0 auto;}
body {
	color:black;
	background-image:url(mars.jpg);
	font-size: 40px;
	margin-left: auto; 
	margin-right: auto;
}
main {
	color:black;
	font-size: 60px;
	position: absolute; /* postulat de départ */
    top: 50%; left: 50%; /* à 50%/50% du parent référent */
    transform: translate(-50%, -50%); /* décalage de 50% de sa propre taille */
}

ul {
list-style:none;
margin-left:0;
padding-left:0;
}