opacity modification for favorites

Now it's only possible with the DisplayPostInfo script from BrokenEagle98 on Danbooru since the attribute got removed 2 years ago.

Only the "data-is-favorited" is needed to apply CSS styles to it.

.post-preview[data-is-favorited="true"] {
    opacity: 0.5;
}

.post-preview[data-is-favorited="true"]:hover {
    opacity: 1.0;
}

Any plans to add it?

I'm not sure about that. It was removed for performance/tech debt reasons and re-adding it would likely have a not-insignificant impact on thumbnail generation time, which is by far the most compute-intensive thing on the site. The desire to use these data attributes is fairly niche.

I added a setting for it to the beta site, we'll see how it goes.