.lock {
    background-image: url("../images/lock.png");
    background-size: 22px 22px;
    background-repeat: no-repeat;
    background-position: center right 10px;
}
.unlock {
    background-image: url("../images/unlock.png");
    background-size: 22px 22px;
    background-repeat: no-repeat;
    background-position: center right 10px;
}