@media screen and (max-width:780px) {
    .main {
        height: 75%;
    }
    .liste_items {
        column-width: 100vw;
    }
}
@media screen and (min-width:780px) {
    .header {
        height: 35%;
    }
    .liste_items {
        column-width: 30vw;
    }
    .main {
        height: 55%;
    }
}