Making a Tab control system smaller

Below is the desktop UI that I'm currently working on and I need to make it much smaller. It is 1266px wide and my task is to make something that is maximum 390 wide. I've been trying to look up UI designs for choosing categories but nothing is jumping out to me or they are mobile designs.

My current thought is to have a bubble system where you hover over the bubble and it expands from there but I'm not sure if that's just rubbish UI as it could go to 3 levels and may not be user friendly.

Any thoughts would be appreciated