Follow-up to the matrix-rain backdrop (merged): address argus's review nit
on the fadeColor construction. It string-rewrote `rgb(...)`→`rgba(...)`,
which silently fills the trail solid if getComputedStyle ever returns a
non-`rgb(r, g, b)` form. Extract r,g,b numerically and build the rgba
explicitly so the trail always fades regardless of the returned format
(same rgb fallback end-to-end). CSS/JS-only, home page.
1bc26429f2