body {
    display: flex;
    justify-content: center;
    align-items: center;
    display: -webkit-flex;
    -webkit-align-items: center;
    -webkit-justify-content: center;
    flex-direction: column;
    -webkit-flex-direction: column;
}

body,
html {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
}