section {
    display: grid;
    grid-template-columns: 1fr 1fr;
}
.w_left {
    padding: 2em;
    text-align: justify;
}
.w_right{
    padding: 2em;
    text-align: justify;
}
#ulist {
    margin-left: 4em;
}
@media screen and (max-width: 650px) {
    .w_left {
        grid-column: 1;
    }
    .w_right{
        grid-column: 2;
    }
    #ulist {
        margin-left: 1.5em;
    }
}
#titre {
    margin: 1em 4em;
    text-align: center;
  }