html, body {
    margin: 0;
    height: 100%;
}
body {
    font-family: Sans-Serif;
    display: flex;
    flex-flow: column;
}
header {
    padding: 0.2rem;
    flex: 0 1 auto;
    overflow: hidden;
    border-bottom: 2px solid rgb(58, 58, 58);
    background-color: lightgray;
    text-align: center;
}
#start-button {
    width: 6rem;
}
#copy-id {
    text-decoration: none;
    color: darkblue;
}
#copy-id .copied {
    color: black;
}
#copy-id .icon {
    color: blue;
    font-weight: bold;
}
main {
    flex: 1 1 auto;
    overflow: hidden;
}
iframe {
    width: 100%;
    height: 100%;
    border: none;
}