html, body {
    width: 100%;
    height: 100%;
    min-height: 100%;
    margin: 0;
    padding: 0;
    overflow: auto;
}

body {
    min-width: 320px;
}

#compose-receiver {
    width: 100vw;
    min-height: 100vh;
}

#compose-receiver canvas {
    display: block;
    width: 100%;
    min-height: 100vh;
}