Shrink Header on Scroll

Page Injections

Settings > Advanced > Code Injection
Insert in Footer

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

<script>
$(function(){
 var visibleTop = 50;
  $(window).scroll(function() {
    var scroll = getCurrentScroll();
      if ( scroll >= visibleTop ) {
           $('header.Header.Header--bottom').addClass('tsticky');
        }
        else {
            $('header.Header.Header--bottom').removeClass('tsticky');
        }
  });
function getCurrentScroll() {
    return window.pageYOffset || document.documentElement.scrollTop;
    }
});
</script>

<style>
  .tsticky .Header-branding {
    font-size: 50px !important;
}
</style>