Better rendering for spans with only client-side annotations

[mjbryant]

This is awesome, thanks for the work! I used this to visualize some of our internal data and noticed that the span display isn't so helpful when server spans are missing. Specifically, they display like this:

It would be nice if the horizontal position was preserved when only client spans were present. Maybe the whole span could be a gray bar, just correctly positioned horizontally?

[rogeralsing]

Ah, yes, I will take a look at that, the code currenty calculates deltas between CS and SR, but ofc in this case it should just get the start and end of CS CR