I need a basic age verification checker for a Shopify site that sells items for those aged over 18 years.
I need the code and instructions where to add it via the site CMS.
The verification needs to check all site visitors no matter which page they land on, ask the visitor to enter their date of birth. If the visitor is 18 or over the visitor is allowed into the site. If they are not a warning is displayed and the visitor is redirected to an alternative site.