[oneeyedpigeon]

It change the background color AND turns off the animation.

(TBF, it slowly fades the animation out, probably for aesthetic reasons, to avoid a jarring sudden stop. I do agree, though, that a sudden stop would probably be more appropriate in this context)

[scythmic_waves]

Ohhh thank you! I thought the same as the parent comment: I expected that button to turn off the animation immediately. I guess the author wanted the yellow background to "melt" the snowflakes?