Phone Box for Bed Loft

I made this for the side of my bed, it's like a bunk bed, except it only has the top part. I bring my phone and a charger cord with me up there and my phone's fallen off my bed a couple times. That is TOO dangerous. It took me too long to make this. Originally, I was going to make a case that held my phone sideways and gripped onto the bars of the bed, but then I realized that building a case that grips on top of another case would be really intricate.

So what I'm going to do is put some velc