CSS - global hover on background property with opacity

Question

.hm-fb, .hm-tw, .hm-evgc, .hm-fecm, .hm-oi {
	display: inline-block;
    background: #3B5998;
    color: white;
    padding: 2px 9px;
    cursor: pointer;
}
.hm-tw {
	background: #55ACEE;
}
.hm-evgc {
	background: #24853c;
}
.hm-fecm {
	background: #4c687d;
}
.hm-oi {
	background: #790e0e;
}
.hm-social-btn a span:hover {
	opacity: 0.8;
}