#masthead.site-header {
    background-image: url('https://saintmartinlestra.fr/wp-content/uploads/2020/05/cropped-Capturecentre1.png') !important;
    background-size: cover !important;
    background-position: center !important;
    background-repeat: no-repeat !important;
    min-height: 400px;
}

/* Rendre l'overlay moins sombre pour que l'image soit visible */
#masthead .overlay {
    background: rgba(0, 0, 0, 0.2) !important;
}