I believe there is no :blur pseudo-class in CSS.
The dynamic pseudo-classes in CSS represent states; they don't represent events or transitions between states in terms of the DOM. To wit: the :focus pseudo-class represents an element that is in focus; it does not represent an element that has just received focus, nor does there exist a :blur pseudo-class to represent an element that has just lost focus.
Similarly, this applies to the :hover pseudo-class. While it represents an element which has a pointing device over it, there is neither a :mouseover pseudo-class for an element that has just been pointed to nor a :mouseout pseudo-class for an element that has just been pointed away from.
If you need to apply styles to an element that is not in focus, you have two choices:
Use :not(:focus) (with less browser support):
input:not(:focus), button:not(:focus) {
/* Styles for only form inputs and buttons that do not have focus */
}
Declare a rule that applies to any element regardless of its focus state, and override for elements that have focus:
input, button {
/* Styles for all form inputs and buttons */
}
input:focus, button:focus {
/* Styles for only form inputs and buttons that have focus */
}
THIS ANSWER WAS ORIGINALLY POSTED BY BOLTCLOCK (HERE)