body {
    font-family: sans-serif;
    text-align: center;
    margin: 0;
    padding: 0;
}
main {
    display: flex;
    height: 100vh;
    flex-direction: column;
    align-items: center;
}
main video {
    max-width: 100%;
    max-height: calc(100% - 6em);
}