body {
  display: flex;
  flex-direction: column;
  position: relative;
  margin: 0;
  padding: 0;
  min-height: 100vh;
  font-family: Arial, sans-serif;
  overflow-x: hidden; /* Empêcher le défilement horizontal */
}
header {
  background-color: #007bff;
  color: #fff;
  padding: 20px;
  text-align: center;
  margin-bottom: 20px;
}
#exercise-links {
  padding: 20px;
  text-align: center;
}
.exercise-link {
  display: inline-block;
  margin-bottom: 10px;
  padding: 10px 20px;
  background-color: #007bff;
  color: #fff;
  text-decoration: none;
  border-radius: 5px;
  transition: background-color 0.3s ease;
  width: 80%;
}
.exercise-link:hover {
  background-color: #0056b3;
}
.img_logo {
  width: 50%;
  height: 50%;
  display: block; /* Afficher l'image comme un bloc */
  margin: 0 auto; /* Marges automatiques pour centrer l'image horizontalement */
}
footer {
  bottom: 0;
  left: 0;
  margin-top: 20px;
  width: 100%;
  background-color: #94949444;
  color: #333;
  padding: 20px;
  text-align: center;
}
#before {
  float: left;
  margin-left: 10%;
  background-color: #007bff;
  color: white;
  font-size: 20px;
  text-align: center;
  border-radius: 5px;
  font-weight: bold;
  border: none;
  width: 30px;
  height: 30px;
}
#before:hover {
  background-color: #0056b3;
}
#after {
  float: right;
  margin-right: 10%;
  background-color: #007bff;
  color: white;
  font-size: 20px;
  text-align: center;
  border-radius: 5px;
  font-weight: bold;
  border: none;
  width: 30px;
  height: 30px;
}
#after:hover {
  background-color: #0056b3;
}