By adding a b2evo HTML widget to a collection skin container Page Top, Header, Front page main area, etc., you may make it snow on your b2evolution collection.

Once the HTML widget is added to your preferred skin container, Settings will open up; inside the Block content field you will paste the HTML tepito... er, snippet, found by opening up in your browser:
https://raw.githubusercontent.com/pajasevi/CSSnowflakes/master/snippet.html (right click => Select all/Copy -- as we only want text, not fancy formatting).

You can enter anything in the Block title field. Save changes and go to display your collection content: snow flakes will be falling (tried with Horizon main skin ;-)

Huelmati [Enjoy]!