HABPanel 2.5 -> 3.x Preparing for upgrade

on my Rasp. 3+ with openhab 2.5.12 am preparing to migrate to the newest stable openhab 3.x version.
Before doing that I wish to “take with me” existing HABPanel based on Matrix Panel Configuration
Since a while I made a lot of improvements to the theme and I wish to take 100% of this what I have achieved with 2.5.x
Reading few post i got confused and decided to ask some more experience members.
Example reading this post it is recommended to expert local version only. I have nothing there. I created not a local one.

My existing Panel configuration looks like that.

So it is not a local version.
How can I export all files including css the way i will be able to import everything to OH3.x?