html {
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
}



#header-box {
    background-color: #333333;
    color: #fff;
    text-transform: uppercase;
}

#box {
    margin: auto;
    width: 50%;
}

tr:nth-child(2n+ 2) {
    background-color: #f2f2f2;
}

tr:hover {
    background-color: lightyellow;
}