Hi,
Your template has CSS caching activated. So Im not sure of the state of the CSS on your website.
What I can say is that your pages are missing the CSS code we had to add to HikaShop for that drawer system to work properly.
Maybe just purging the CSS cache of the template will be enough ?
Or maybe you had to turn off the use of HikaShop's CSS file to rely only on the CSS from the template and in that case, even after purging the CSS cache, you would still be missing the CSS to handle the drawer mechanism properly.
So, first, I would recommend purging the CSS cache and see how it goes.
If that doesn't help, please temporarily turn off the CSS caching so that we can properly investigate the situation.