Build the CSS linear-gradient(to right, …) string that paints the scrubber track with the day's color bands.
linear-gradient(to right, …)
The day's bands, e.g. from computeTimelineBands.
A CSS linear-gradient(...) value (hard color stops at each band edge). Falls back to the solid night color when bands is empty.
linear-gradient(...)
bands
Build the CSS
linear-gradient(to right, …)string that paints the scrubber track with the day's color bands.