.btn_banniere.wp-block-buttons:after {
    content: "";
    background-image: url(/wp-content/themes/francecom/img/svg/jaunehome.svg);
    -webkit-background-size: 100% 100%;
    display: block;
    width: calc(100% + 29rem);
    height: 14rem;
    position: absolute;
    bottom: -3rem;
    z-index: -1;
}