.element1 {
    height: 200px;
    width: 200px;
    background-color: green;
    opacity: 1;
    margin: 20px;
}
.element2 {
    height: 200px;
    width: 200px;
    background-color: green;
    opacity: 0.5;
    margin: 20px;
}
.element3 {
    height: 200px;
    width: 200px;
    background-color: green;
    opacity: 1;
    margin: 20px;
}