div{ 
    width: 300px;
    margin: 0 auto; 
 }

 h1{ 
    text-align: center;
 }

.first, .second, .third, .fourth{
 float:center;
        width : 70%;
        display: flex;
        flex-flow: row wrap; 
        color: white;
        border-radius: 10em;
        padding:15px;
        margin: auto;
        text-align:center;
    }

.ctr{
    text-align: center;
}

.first{
    background: limegreen;
}

.second{
    background: turquoise;
    margin-top: 20px;
}

.third{
    background: orange;
    margin-top: 20px;
}

.fourth{
    background: red;
    margin-top: 20px;
}