Background — Lines
White lines wander down a dark canvas, bowing into S-curves and drifting out of phase, while their number swells and shrinks between two bounds.
A few white lines span the canvas top to bottom, each bowing sideways into an S-curve and swaying on its own phase, so they split apart and rejoin as they drift. Their count grows and shrinks smoothly over the loop.
The count is a fractional number eased between a minimum and a maximum on a cosine: the whole part draws fully opaque lines while the fraction fades the newest one in and slides it across from the edge, so lines are born progressively instead of popping into place. Each line is a polyline whose horizontal drift is an easing curve evaluated along its own height — the default back-ease overshoot is what bends it into the S — with the sway phase offset per line.
