html {
    height: 100%;
    padding: 0;
    margin: 0;
    max-height: 100%;
}
body {
    min-height: 100%;
    background-color: #eee;
    padding: 0;
    margin: 0;
    max-height: 100%;
}

.grid {
    display: grid;
    grid-template-rows: 80px 1fr;
    height: 100vh;
}

header {
    align-self: center;
}

main {
    align-self: start;
    height: 100%;
}

iframe {
    width: 100%;
    height: calc(100% - 10px);
    padding: 0;
    margin: 0;
    border: none;
}