html,
body {
    margin: 0;
    width: 100%;
    height: 100%;
    background-color: #22252C;
}

div { position: absolute; }

/* keep the controls outside the flow and visible regardless how the visualization unfolds */
.controls {
    position: absolute;
    z-index: 999;
    color: #ccc;
    padding: 5px;
    margin: 12px;
    border-radius: 3px;
}

.controls label {
    vertical-align: 4px;
    font-family: system-ui;
    font-size: 12px;
}