body {
    background: lightgray;
    font-family: sans-serif;
    margin: 0;
    height: 100vh;
}

body > div {
    box-sizing: border-box;
    background: lightgray;
    /* border: 1px dashed black; */
    width: 85%;
    height: 90vh;
    margin: auto;
    text-align: center;
    border-radius: 4px;
    padding-bottom: 50px;
    padding-top: 20px;

    box-shadow: 0px 1px 25px 1px rgba(0,0,0,0.25);
    -webkit-box-shadow: 0px 1px 25px 1px rgba(0,0,0,0.25);
    -moz-box-shadow: 0px 1px 25px 1px rgba(0,0,0,0.25);
}

video {
    /* max-width: 100%; */
    /* height: auto; */
    width: 640px;
    height: 480px;
}

@media only screen and (max-width: 800px) {
    body {
        background-color: gray;
    }

    body > div {
        box-sizing: border-box;
        width: calc(100% - 10px);
        height: calc(100% - 10px);
        margin: 5px;
    }

    video {
        width: 100%;
        height: 240px;
    }
}