img[src="img/union01.jpg"]:hover {
   opacity: 0.5;
}

img[src="img/union02.jpg"]:hover {
   opacity: 0.5;
}

img[src="img/union03.jpg"]:hover {
   opacity: 0.5;
}

img[src="img/union04.jpg"]:hover {
   opacity: 0.5;
}

img[src="img/union05.jpg"]:hover {
   opacity: 0.5;
}