When you open ebay product collections, you’ll see that they have images with #f6f6f6 background:
https://www.ebay.com/b/Collectible-Sneakers/bn_7000259435?
enter image description here

But when you open the image in a new tab, the image has white BG.

I suspect it has some css doing this but I don’t know what. Can anyone help me out so that I can implement this on my website as well.

Thanks.

I have tried filter: greyscale with different settings but it turns the whole image into greyscale and not just the white part.