Edit File: classic.min.css
.wp-block-button__link{background-color:#32373c;border-radius:9999px;box-shadow:none;color:#fff;font-size:1.125em;padding:calc(.667em + 2px) calc(1.333em + 2px);text-decoration:none}.wp-block-file__button{background:#32373c;color:#fff}