nav {
    display: flex;
    padding:  5px;
    justify-content: space-around;
    color: #000;
    background-color: #aaa;
}

p a{
    text-decoration: none;
    color: #000;

}

nav p a:hover{

    color: #fff ;
}

main {
    display: flex;
    flex-direction: row;
    justify-content: flex-start;
}


h1, h2, h3{
    margin: 0;
}
  .main-header {
    display: flex;
    flex-direction:column;
    justify-content: left;
      background-color: grey;
      padding:  5px;
      color:  #fff;
      background-color: #666;

  }

  .main-header h1, .main-header h2 {
      margin: 0;
  }

  aside {
    padding:  5px;
    flex-direction: column;
      display: flex;
      flex-basis: 20%;
      flex-grow: 0;
      flex-shrink: 0;
      background-color: #eee ;
  }

  aside a{
      color: black;
      text-decoration: none;
      text-align: center;
  }

  aside a:hover{
    color: #fff;
    text-decoration: none;
}

  .slogan {
    background-color: grey;
    padding:  5px;
  }

  .topnav{
      background-color: lightgray;
      overflow: hidden;
      padding:  5px;
  }

footer{
    background-color: #666;
    color: #fff;
    padding:  5px;
    display: flex;
    justify-content: center;
}

.conteneur {
    max-width: 980px;
    margin: auto;
}



   @media (max-width: 640px) {
       nav{
           flex-wrap: wrap;
       }

       main {
           flex-direction: column;
       }
       section{
           order: 1;
       }
       aside{
           flex-direction: row;
           align-items: baseline;
       }

       aside p:not(:last-child):after {
           content: "-\00a0";
       }

       aside p::before {
        content: "\a0";
    }

    }

  }