<div class="container">
    <p>My GnuPG fingerprint is <code class="fingerprint">6720 DB3C 03FF DDF1 3838 7D4A A49A 64DF 5B42 3590</code>.</p>
</div>
.container {
    margin-top: 2em;
    text-align: center;
}

.fingerprint .number {
    color: darken(#bd4147, 25%);
}
$(document).ready(function() {
    var regexNumber = /(\d+)/g;
    
    $('.fingerprint').each(function(index) {
        var codeFingerprintText = $(this).text();
        $(this).html(
            codeFingerprintText.replace(
                regexNumber,
                '<span class="number">$&</span>'
            )
        );
    });
});

External CSS

  1. http://old-fashioned.mylesbraithwaite.org/assets/toolkit/styles/toolkit.css

External JavaScript

  1. //cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js