a.c-button__btn.c-button__btn--primary.c-button__btn--icon[href*="://member.jp.yamaha.com/"] {
    padding: 15px;
    color: #fff !important;
    background: #000;
    border-radius: 0px;
    display: block;
}

a.c-button__btn.c-button__btn--primary.c-button__btn--icon[href*="://member.jp.yamaha.com/"] span {
    color: #fff !important;
}

a.c-button__btn.c-button__btn--primary.c-button__btn--icon[href*="://member.jp.yamaha.com/"]:hover,
a.c-button__btn.c-button__btn--primary.c-button__btn--icon[href*="://member.jp.yamaha.com/"]:focus {
    text-decoration: underline;
}