Add to css in child theme, and adjust colors accordingly:

/* Read more blog button */

.more-link {
background-color: #1f568e;
display: inline-block !important;
color: #fff;
padding: 5px 15px;
margin-top: 15px;
text-transform: uppercase;
}

.more-link:hover {
background-color: #3683d2;
}