I have just taken a look at the URL you shared and it appears theAdd to cartbutton is visible and functioning on the product page, are you still having trouble viewing this on your end?
By the way, while looking around your store I noticed that Powered by Shopify is shown in your footer. Did you know that if you remove or change this to your store's name, it will give your site its own identity and distinction? I'll leave aquick guide herefor you just in case you wanted to learn how to remove it orwatch this videoif you would prefer a visual how to.
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