What is pseudo class

CSS pseudo-class is a keyword added to a selector that lets you style a specific state of the selected element(s).

What is disabled

CSS pseudo-class representing a disabled element.

Disabled element can't be activated (selected, clicked, typed into, etc.) or accept focus.

*:disabled {
  background-color: dimgrey;
  color: linen;
  opacity: 1;a
}

input[type="text"]:disabled {
  background: #ccc;
}

Opposite of :disabled is :enabled.