body{
  font-family: Arial, Helvetica, sans-serif;
  cursor: crosshair;
  font-size: 150%;
}

html {
  height: 100%;
  width: 100%;
}

nav {
  margin: 20px auto;
  width: 100%;
  height: 100px;
  border-radius: 20px;
  background: linear-gradient(90deg, #00364a, #006d8f);
  box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
  opacity: 70%;
  border: solid 2px;
}

nav .main_pages {
  display: flex;
  justify-content: space-around;
  align-items: center;
}

nav .main_pages a {
  width: 20%;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100px;
  text-decoration: none;
  font-family: Arial, sans-serif;
  color: white;
}

nav a:hover {
  background:#00364a;
  border-radius: 20px;
}


.Titre1 {
  background-color: #d6d6d6;
  font-size: 70px;
  font-weight: bold;
  text-align: center;
  border-radius: 5px;
  
}

.titre-top {
  text-align: center;
}

.titre-chemin {
  text-align: center;
}

iframe {
  display:block;
  margin: 20px;
  width: 50%;
}

.arrier{
  width: 50%;
  margin-left: 25%;
  font-size: 30px;
}

.arrier img{
  width: 70%;
}