Hi there, @maggieh. 👋
Unfortunately, we don't support media keys for the web browser. You would need to use the keyboard shortcuts instead. The media keys (volume, play/pause, skip) on your keyboard can be used to control playback on the Pandora Desktop app.
You can also select Controls at the top of the Mac menu bar, for the Pandora app, to review all Keyboard shortcuts available when the app is in focus.
Here's a quick list:
Items will be greyed out when playing a source that does not support that command.
If your computer is upgraded to macOS Mojave and you are having trouble using these shortcuts, please use the following steps to make sure the app has access.
Hope this helps clarify. 🎧