sticky-sidebar.php

// Guideline
// Parent div after body `.prnt_sti`
<div class="prnt_sti">
  <div class="container">
    <div class="sticky-form">
      <div class="sticky-form-inner">

      </div>
    </div>
  </div>
</div>

<style>
  .container {
      position: relative;
  }
  .sticky-form {
      right: 0;
  }
  .sticky-form-inner {
      position: sticky;
      top: 124px;
  }
</style>

<script>
function sidebarSticky() {
    height = jQuery('.prnt_sti').height();
    if( jQuery(window).width() >= 768 ) {
        jQuery('.sticky-form').css({'height':height-100,'position':'absolute','top':'-180px'});
    } else {
        jQuery('.sticky-form').css({'height':'auto','position':'relative','top':'auto'});
    }
}
window.addEventListener('load', function(){
    sidebarSticky();
});
window.addEventListener('resize', function(){
    sidebarSticky();
});
</script>