:root {
      --primary: #d62828;
      --secondary: #003049;
      --bg: #f9f9f9;
      --white: #ffffff;
      --text: #333333;
      --text-light: #555555;
      --radius: 8px;
      --transition: 0.3s ease;
    }

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

    body {
      font-family: 'Segoe UI', sans-serif;
      background: linear-gradient(to right, #eff6ff, #d1fae5);
      color: var(--text);
      line-height: 1.6;
    }

    header {
  background: var(--white);
  text-align: center;
  padding: 2rem 1rem;
  position: fixed;      /* Fixe l'entête */
  top: 0;               /* Collé en haut */
  left: 0;
  width: 100%;          /* Prend toute la largeur */
  z-index: 1000;        /* Passe devant le reste */
  box-shadow: 0 2px 8px rgba(0,0,0,0.1); /* petite ombre élégante */
}




    header h1 {
      font-size: 2rem;
      margin-bottom: 0.5rem;
      color: var(--secondary);
    }

    header p {
      font-weight: 400;
      font-size: 1.1rem;
    }

    .span1_header {       color: #2563eb;}

    /* Comme le header prend de la place, on ajoute un espace en haut du contenu */
main {
  max-width: 1300px;
  margin: 8rem auto;
  padding: 6rem 1rem 0 1rem;  /* <-- ajout d’un padding-top plus grand */
}

    .intro {
      text-align: center;
      font-size: 1.05rem;
      color: var(--text-light);
      margin-bottom: 2rem;
    }

    .cards {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 1.5rem;
      align-items: stretch;
    }

    .card {
      background: var(--white);
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: 0 4px 15px rgba(0,0,0,0.2);
      display: flex;
      flex-direction: column;
      transition: transform var(--transition), box-shadow var(--transition);
    }

    .card:hover {
      transform: translateY(-5px);
      box-shadow: 0 8px 25px rgba(0,0,0,0.15);
    }

    .card img {
      width: 100%;
      height:200px;
      object-fit: cover;
      display: block;
    }

    .card-content {
      padding: 1rem 1.5rem;
      display: flex;
      flex-direction: column;
      flex: 1;
    }

    .card-content h3 {
      font-family: 'Montserrat', sans-serif;
      font-weight: 600;
      color: var(--secondary);
      font-size: 1.25rem;
      margin-bottom: 0.75rem;
    }

    .card-content p {
      color: var(--text-light);
      font-size: 0.95rem;
      margin-bottom: 1rem;
    }

    footer {
      text-align: center;
      padding: 1rem;
      font-size: 0.9rem;
      color: var(--text-light);
      background: var(--white);
      margin-top: 2rem;
    }

    .back-btn {
      display:inline-block;
      padding: 0.7rem 1.2rem;
      background: linear-gradient(to right, #1e3a8a, #15803d);
      color: #fff;
      text-decoration:none;
      border-radius: 6px;
      font-weight:600;
      transition:0.3s;
      margin: 2rem auto;
      text-align:center;
    }

    .back-btn:hover {
      opacity: 0.9;
    }


    @media (max-width: 768px) {
      header { padding: 1rem; }
      header h1 { font-size: 1.2rem; }
      header p { font-size: 0.9rem; }
      .card-content h3 { font-size: 1rem; }
      .card-content p { font-size: 0.85rem; }
      main { padding-top: 5rem; }
    }