General discussion

I have a big problem. I create a hello world greeting card. But when I open it on my cell phone, it doesn't fit the screen properly. I have attached two photos. One is from the phone. The other is from the desktop.

Did I do something wrong? I need it to fit all screen sizes.

In the course presentation, how can I play an audio in the transition?

If I make a custom library, do I create my own Machine Name? Or, do I have to use an existing Machine Name?