You can download sticky-panel.css and sticky-panel.php from this page – https://dropmefiles.com/JqPCG
1/ sticky-panel.php file content (I left details in the top of file but write them below again)
// copy and add next code to your child-theme/functions.php
2/ sticky-panel.css – file content (I left details in the top of file but write them below again)
// copy next custom style to your child-theme/style.css
