It's currently not possible or at least not that easy to do, the browser saves the game files in the cache directory but the files themselves are encrypted so the desktop/android version of the game won't recognize them as valid save files.
I will try to add the possibility to import/export save files in the near future so they can be exchanged between all the platforms.
Note :
If you find any tool that can decrypt the browser's cache data then it may be possible. the save files will have the ".rxdat" extension and then you can move them to the "Appdata/Roaming/CrystalSprings" directoty to appear in the offline version.