center An argument to Particle.withLocation that determines the horizontal center of viewport where you would like confetti to rain.
You will need to watch for page resize events and update the confetti model with the new width. If you don't, your confetti will be off-center.
Why is this not part of subscriptions? Your application may already be listening for browser resize events -- we don't want to double-up listeners unnecessarily.
Changes from V1: