body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background: linear-gradient(45deg, #8e44ad, #3498db); 
    display: flex;
    flex-direction: column;
    align-items: center;
    height: 100vh;
    text-align: center;
    color: white;
  }
  
 
  header nav {
    background-color: rgba(52, 152, 219, 0.8); 
    width: 100%;
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 10;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  }
  
  header nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
  }
  
  header nav ul li {
    margin: 0 20px;
  }
  
  header nav ul li button {
    padding: 10px 20px;
    background-color: #2980b9;
    color: white;
    border: none;
    font-size: 18px;
    cursor: pointer;
    border-radius: 25px;
    transition: all 0.3s ease;
  }
  
  header nav ul li button:hover {
    background-color: #3498db;
    transform: scale(1.1);
  }
  
  header hr {
    width: 60%;
    border: 1px solid #3498db;
    margin: 20px 0;
  }
  
  #contenu {
    width: 80%;
    max-width: 1200px;
    margin-top: 50px;
  }
  
  .contenu-section {
    display: none;
    margin: 40px 0;
    animation: fadeIn 1s ease-out;
  }
  
  @keyframes fadeIn {
    0% {
      opacity: 0;
      transform: translateY(20px);
    }
    100% {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  .carre-violet {
    width: 300px;
    height: 300px;
    background-color: #8e44ad; 
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 25px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .carre-violet:hover {
    transform: scale(1.1);
    box-shadow: 0 15px 25px rgba(0, 0, 0, 0.4);
  }
  
  .carre-interieur {
    width: 80%;
    height: 80%;
    background-color: #9b59b6; 
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    text-align: center;
    color: white;
    font-size: 18px;
    cursor: pointer;
    transition: all 0.3s ease;
  }
  
  .carre-interieur p {
    margin: 0;
    font-weight: bold;
  }
  
  @keyframes afficherTexte {
    from {
      opacity: 0;
      transform: translateY(-20px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  #programme-texte {
    display: none;
    animation: afficherTexte 1s forwards;
    font-size: 16px;
    text-align: center;
    margin-top: 20px;
    color: #f39c12;
  }
  
  p {
    font-size: 18px;
    line-height: 1.6;
    max-width: 800px;
    margin: 0 auto;
  }
.back-button {
  position: fixed; 
  bottom: 20px;  
  left: 20px; 
  padding: 12px 20px;
  font-size: 18px;
  color: white;
  background-color: #3498db; 
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.back-button:hover {
  background-color: #2980b9; }