A dark theme can be a good contrast on a light-themed page. This example also features a product logo and button.
<aside class="mzp-c-sticky-promo mzp-t-dark mzp-t-product-developer">
<button class="mzp-c-sticky-promo-close" type="button">Close</button>
<h3 class="mzp-c-sticky-promo-title">Get the browser made for developers</h3>
<p><a href="#" class="mzp-c-button mzp-t-product mzp-t-lg">Download Now</a></p>
</aside>
<button id="showSticky" class="mzp-c-button" type="button">Show Sticky Promo</button>
<script src="../../protocol/js/sticky-promo.js"></script>
<script>
(function() {
'use strict';
var showStickyBtn = document.getElementById("showSticky");
showStickyBtn.addEventListener('click', MzpStickyPromo.open, false);
})();
</script>