html, body {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    line-height: 1.5;
}
#container {
    margin: 0 auto;
    width: 340px;
    height: 100%;
    max-width: calc(100% - 40px);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    font-family: 'Courier New', Courier, monospace;
    box-sizing: border-box;
}

h1 {
    margin-bottom: 0;
    margin-top: 0.5em;
}

footer {
    width: 100%;
}