How to style buttons on a single page

I've created a new page and want to test out a new button colour. I don't want to change it globally across the site, just all buttons on this page. I've tried reading documentation, but I can't figure this out. The page in question is - https://wrpartners.co.uk/hr-advisory-1

You can add this code to HR Advisory-1 Page Header

<style>
  .button-block a {
    background-color: #f1f !important;
    color: black !important;
}
</style>