If you are using Danland 7.x and modify it using local.css, then it should not be any problem to directly upgrade to 8.x. The 8.x-1.x branch is for compatibility with older version (7.x), so for new features it should goes to 8.x-2.x branch.
First, uncomment #css/local.css: {} in danland.libraries.yml, and place local.css to the css folder and clear your Drupal cache.
The superfish menu for Danland 8.x not added yet since I'm planning to use existing contrib module and we just need to styling it.
Danblog?