html, body {
    height: 100%;
    margin: 0;
}

#glcanvas {
    position: fixed; /* follow the viewport */
    inset: 0; /* top:0; right:0; bottom:0; left:0 */
    z-index: 0; /* behind everything */
    width: 100%;
    height: 100%;
    display: block;
    pointer-events: none; /* don't intercept mouse/touch */
    mask: radial-gradient(86% 150% at 86.8% 45.7%, rgba(0, 0, 0, 0) 31.2993%, rgb(0, 0, 0) 100%), linear-gradient(296deg, rgba(0, 0, 0, 0) 48%, rgb(0, 0, 0) 77%);
    opacity: 0.4;
}

#main {
    position: relative; /* ensure its own stacking context */
    z-index: 0; /* above the canvas */
}

/* Optional: a tiny settings block, toggle display to see/change props live */
#ui {
    position: fixed;
    left: 12px;
    top: 12px;
    padding: 10px 12px;
    font: 12px/1.4 system-ui, sans-serif;
    background: #0008;
    color: #eee;
    border: 1px solid #fff2;
    border-radius: 8px;
    backdrop-filter: blur(6px);
}

#ui input[type=range] {
    width: 160px;
}

#ui label {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 8px;
    align-items: center;
    margin: 6px 0;
}