body {
    padding:0;
    margin:0;
    background: black;
    color: white;
}

dialog {
    position:relative;
}

#canvas {
    margin: 0;
    padding: 0;
    background: #ffffff;
    border: none;
    width: 100%;
    height: 100%;
}

.container {
    display: flex;
}

.container__sidebar {
    width: 30%;
}

.container__main {
    /* Take the remaining width */
    flex: 1;
}

.btn {
    margin: .25rem .125rem;
}