How to make a multiple vertical grayscale bands background?

[Иван Никитин]

My App receives ticks with float and datatime values.

Float goes to common graph which is placed foreground. Datatime and previuos datatime as timedelta turn gray color; more time passed -> darker gray color. And on background of each float I want to see an infinite vertical grayscale band. This bands must cover all background space.

As the X-axis ्data is a list elements count 0, 1, 2, etc then width of each band will be the same.