On the index page:
<% @products.each do |prod| %>
<%= render 'shared/product_card', product: prod %>
<% end %>
In my product card partial:
<div class="product-card-image" style='background-image: url("<%= product.name %>.jpeg")'></div>
I can't hard-code the images into the CSS as background since they are different for each product of course.
In the views you need to call asset_url(product) for the URL to render correctly, pointing to the compiled asset.
Please view these docs here to see how to render the assets in different ways: https://guides.rubyonrails.org/asset_pipeline.html#css-and-sass
Try:
<div class="product-card-image" style='background-image: url(<%= asset_path('product.png') %>)'></div>
Inline styles are not preferred, If I were you I might try to render the actual image tag for the image in the view, and position it in the div with object-fit css directives, placing other content on top of it. This will allow you to avoid the pitfalls of CSP and style tags.