What's up with Semantic-UI?

packages
12

I’m having trouble getting the package to work unless I use the default option and enable all features, in which case the generated .css file is biiiiiiiiiig.

If I try to single out ‘buttons’ and a few others I get:

=> Errors prevented startup:                  
   
   While processing files with flemay:less-autoprefixer (for target web.browser):
   client/lib/semantic-ui/theme.import.less:20: Unknown import: themes/default/globals/site.variables.import.less

Any help much appreciated.

Edit: I found this thread but it’s all greek to me: