.firecheckout-set {
    counter-reset: firecheckout-section-number;
}
#billing-address > .block-title::before,
#shipping-method > .block-title::before,
#payment-method  > .block-title::before,
#checkout-review > .block-title::before {
    counter-increment: firecheckout-section-number;
    content: counter(firecheckout-section-number);
    font-family: Verdana, sans-serif;
    font-size: 12px;
    margin: 0 7px 0 0;
    background: #000;
    color: #fff;
    font-weight: normal;
    vertical-align: top;
    display: inline-block;
    width: 22px;
    height: 22px;
    text-align: center;
    line-height: 22px;
}