When I start a Pluto notebook, the first cell contains the message Happy holiday! Remember to take care of yourself and your loved ones! and there’s an animation going on on the notebook, with falling snow. I would like the notebook to start without that animation and message. I found the package PlutoStyles but before diving into the CSS I was wondering if there’s a simpler solution.
Does an update of pluto work? I don’t get those cells and I think it was only included in a special release.
Maybe the animation is also triggered by a function call inside the notebook.
Does that cell call any special functions in addition to printing a message?
Indeed, updating the package removes that extra cell, which was also responsible for the modified theme: deleting it gets rid of the snow flakes 
Thank you!