Hello,
Why this is working: http://nascar.adrenalinex.co.uk/home/wp-content/themes/arras/gallery/gallery.html
and when I include this file in home.php it’s broken? It’s just HTML, JavaScript not working then at all http://nascar.adrenalinex.co.uk/home/
It looks like everything on the home page is actually working fine.
It won’t work as a separate HTML file because (apart from the fact it’s not a fully formed HTML page) the required JavaScript (and maybe CSS) isn’t in that file.