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;
}