/* Fixed background canvas — sits behind all page content */
#bgCanvas { position: fixed; inset: 0; width: 100%; height: 100%; pointer-events: none; z-index: 0; }

/* All body children except canvas and scroll-line sit above the canvas */
body > *:not(#bgCanvas):not(#scroll-line):not(.float-btns) { position: relative; z-index: 1; }