.button{
        display: inline-block;
        width: 150px;
        height: 150px;
        border-radius: 75px;
        background-color: #e0e0e0;
        position: relative;
        vertical-align: center;
        line-height: 150px;
    }

body {
    text-align: center;
    vertical-align: center;
}