Is there any css to differentiate loaded tabs from unloaded?

[scmanjarrez]

I meant, to have a grayed out tabs that haven't been loaded yet (you click it, then it refresh and web content)

[MrOtherGuy]

For that you can simply use something like this:

.tabbrowser-tab[pending]{
  opacity: 0.4;
}

[scmanjarrez]

Thank you!