.wp-block-file .wp-block-file__button {
    background: #C64148;
    border-radius: 2em;
    color: #f9f9f9;
    font-size: 13px;
    padding: .5em 1em;
}
.wp-block-file .wp-block-file__button a:hover{
    background: #C4ced3;
    border-radius: 2em;
    color: #f9f9f9;
    font-size: 13px;
    padding: .5em 1em;
}