message: art: Sommaire sur l'accueil plus compact
diff: .landing-explanation h2 {
  text-align: center;
  + margin-bottom: 0.3em;
  }
  .landing-explanation p {
  text-align: center;
  align-items: center;
  justify-content: flex-start;
  }
  +.landing-explanation li {
  + margin-bottom: 0.4em;
  +}
  .landing-explanation img {
  width: 72px !important;
  