html,
body {
    margin: 0;
    padding: 0;
    background-color: #223;
    color: #fffd;
    font-family: sans-serif;
}

header {
    margin: 1em 0;
    padding: 0;
    display: grid;
    place-items: center;
}

header > video {
    max-width: calc(100vw - 2em);
    margin: 0;
    mix-blend-mode: screen;
    border-radius: 50%;
}

main {
    display: grid;
    grid-template-columns: 1fr min(90vw, 700px) 1fr;
}

main > section {
    grid-column: 2/3;
}