.demo3 div {
    display: inline-block;
    width: 40px;
    height: 40px;
    margin: 5px;
    background-color: #e0e0e0;
    text-align: center;
    line-height: 40px;
    border-radius: 4px;
}
.demo3 div:nth-of-type(3n+2) {
    background-color: #ff9800;
    color: white;
    font-weight: bold;
    transform: scale(1.1);
}