              +button(gh("spacy", source), false, "secondary", "small").u-nowrap.u-float-right
                  span Source #[+icon("code", 14).o-icon--inline]
  
  
  //- External links
      url     - [string] link href
      trusted - [boolean] if not set / false, rel="noopener nofollow" is added
                info: https://mathiasbynens.github.io/rel-noopener/
  
  mixin a(url, trusted)
 
</s>
//- Permalink rendering
    id - [string] permalink ID used for link anchor

mixin permalink(id)
    if id
        a.u-permalink(href="##{id}")
            block

    else
        block


              +button(gh("spacy", source), false, "secondary", "small").u-nowrap.u-float-right
                  span Source #[+icon("code", 14).o-icon--inline]
  
  
//- Permalink rendering
    id - [string] permalink ID used for link anchor

mixin permalink(id)
    if id
        a.u-permalink(href="##{id}")
            block

    else
        block


  //- External links
      url     - [string] link href
      trusted - [boolean] if not set / false, rel="noopener nofollow" is added
                info: https://mathiasbynens.github.io/rel-noopener/
  
  mixin a(url, trusted)
keep keep keep add keep keep keep keep keep keep
 Merge mixins and mixins-base

The distinction was never clear anyways and it was progressively getting messier. So all mixins live in one file now.
website/_includes/_mixins.jade