Minimal theme

1. In your Shopify Admin click Online Store .
2. Click to Current Theme's Actions > Edit code.
3. Open the product-template.liquid file under the Sections area of your Theme Editor.
4. Copy the code below.

   {% unless product.metafields.coattend.enabled %}
    <button type="submit" name="add" id="AddToCart" class="btn {{ btn_class }}{% if section.settings.enable_payment_button %} btn--secondary{% endif %}">
        <span id="AddToCartText">{{ 'products.product.add_to_cart' | t }}</span>
    </button>
    {% if section.settings.enable_payment_button %}
        {{ form | payment_button }}
    {% endif %}
   {% else %}
    <div id="AddToCart" class="coattend-button {{ btn_class }}{% if section.settings.enable_payment_button %} btn--secondary{% endif %}" data-coattend-product-id="{{product.id}}" data-coattend-variant-id="{{product.selected_variant.id}}"><span id="AddToCartText">{{ 'products.product.add_to_cart' | t }}</span></div>
   {% endunless %}

5. Replace code from line 213 to 218. You can see what needs to be replaced on the below image. Minimal theme code that needs to be replaced.
6. Click Save

Congratulations! Continue and display your event.