How can I fade out sold out product images on collection pages?

[Scale164]

Hello, does anyone know the code so I can make SOLD OUT product images fade out on collection pages? I'm using Refresh theme. TIA

[Asad24]

Go to coolection page code file and write this code

{% if product.available = false %}

.product-card {
opacity: 0.5;
transition: opacity 0.3s ease-in-out;
}
{% endif %}

[Scale164]

Sorry, doesn't work.
Where can I find the collection page liquid file on Refresh theme?