html {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    width: 100%;
    height: 100vh;
}

body {
    background: linear-gradient(#eee, #aaa);
    text-align: center;
    /*align-items: center;*/
}

div {
    padding: 5% 0%;
}
.span {
    font-size: 4rem;
    font-weight: bolder;
}