header {
    background-color: #2d2d2d;
    color: #fff;
    padding: 15px 0;
    position: fixed;
    width: 100%;
    }
    
    nav.menu_bandeau_supp ul {
    list-style: none;
    padding: 0;
    margin: 0;
    text-align: center;
    }
    
    nav.menu_bandeau_supp ul li {
    display: inline;
    margin: 0 10px;
    }
    
    nav.menu_bandeau_supp ul li a {
    color: #fff;
    text-decoration: none;
    transition: background-color 0.3s ease;
    }
    
    nav.menu_bandeau_supp ul li a:hover {
        color: #f00;
    }

    nav.menu_bandeau_supp ul li a:active {
        color: #f00;
    }

    
    .image-container{
        display: flex;
        align-items: center;
        justify-content: center;
        padding: 40px 0;
        margin-top: 20px;
    }

    .image-container img{
        max-height: 300px;
        width: auto;
        max-width: 100%;
    }



    @media (max-width: 800px) {
    nav.menu_bandeau_supp ul {
    display: flex;
    flex-direction: column;
    }
    
    nav.menu_bandeau_supp ul li {
    display: block;
    margin: 10px 0;
    }

    header{
        position: static !important;
    }
    }