It takes over 10 seconds to turn off fully. I had to go back and try it after your comment, because I thought that button just turned the page yellow, which was worse than the blue.
I ended up using reader mode to read the page. The whole site design undermined the point being made. One of the first things mentioned is not to be distracting. Yet they went out of their way to make their own site distracting. "Do as I say, not as I do."
I literally didn't notice that the snowflake icon turned it off:
1. I scrolled through the article getting more and more frustrated with the snow
2. I scrolled all the way back to the top and saw the snowflake icon
3. I clicked the snowflake, saw the hideous yellow, said WTF and clicked again to go back to blue
4. **I never noticed** that the snowflake *does* stop the snow, but *only* stops *new* snow, so the existing snow continues to fall across the screen
5. I clicked several other things, then came here to complain and saw this thread