Here is an easy way you can customize button colors. The same principle works for any CSS element on the screen. You can add a HTML snippet to the header and footer and it will appear on all pages in your site, or you can just add this code below your primary Text-Image element to change the color of the button only on this one page.  The example below changes the button color to BLACK instead of the default blue.

<style>
.button {background-color:#000000}
</style>