html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: Helvetiva, Arial, sans;
    color: #BBB;
    display: -webkit-box;
    display: -moz-box;
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;
    align-items: center;
    justify-content: center;
}
h1 {
    font-size: 3em;
    font-weight: 300;
    display: inline-block;
    text-align: center;
    margin: 1em;
}
@media all and (max-width:600px) {
    h1 {
        font-size:2.5em;
    }
}
@media all and (max-width:400px) {
    h1 {
        font-size:1.5em;
    }
}
@media (prefers-color-scheme: light) {
    html, body {
        background-color: #FFF;
        color: #BBB;
    }
}
@media (prefers-color-scheme: dark) {
    html, body {
        background-color: #000;
        color: #444;
    }
}