styles.css

html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: rgb(51, 51, 51);
}

#canvas {
    width:  100%;
    margin:  0px;
    height: 100%;
    background: rgb(51, 51, 51);
}

.dg li.gui-stats:not(.folder) {
    height: 48px;
}

select {
    width: 169px;
}

#gltf-rv-model-spinner {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    margin: auto;
    border: 16px solid #f3f3f3;
    pointer-events: none;
    border-top: 16px solid #86C540;
    border-radius: 50%;
    width: 100px;
    height: 100px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}