NOTE: This setting should only be used by developers. Most shops should leave this option blank. The default behavior of the "Add to Cart Pop-up" feature is to trigger when a visitor clicks the "Add to Cart" button on the product page. In rare cases, a shop might need to specify an element (css selector) to be clicked, in order to trigger the pop-up.To change the trigger element, navigate to Settings -> Quickview & Popup -> Upsell Pop-up -> Trigger Element‍

The trigger element must be a css selector. Examples:
.add-to-cart

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or#product-form-btn

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or if using various classes (i.e. for mobile, tablet & desktop)

‍.atc-desktop, .atc-mobile

‍When in doubt contact us at support@csell.co and our support team can advise.