.wpcf7-date {
    width: 100%;
}

    .wpcf7-date:before {
        width: 100%;
        content: attr(placeholder);
    }

    .wpcf7-date:hover:before {
        width: 0%;
        content: "";
    }

    .wpcf7-date.placeholderclass:before {
        width: 0%;
        content: "";
    }