It can be hard to tell why a mixin fails in a sass file. After all, if the mixin isn't included in your dependencies automatically as it was before, grepping for it in the files won't turn up anything. I was using a child theme of Classy, running Drupal 8. It turns out that this particular generically-named mixin comes from susy 2.x, having been removed in susy 3.x. I fixed this by pinning the susy version number in package.json…
Read more about Error: no mixin named container or border-box-sizingClient has a bunch of static landing pages that are mobile-friendly and need to remain that way. But what is to be done about srcset? Read on, oh reader, for the solution. First, I created a gulp build task which makes a bunch of different sizes. Install dependencies like this: npm install -D gulp-load-plugins gulp-responsive sharp. The task uses gulp-responsive to generate multiple image sizes from a source directory…
Read more about Drupal srcset in static HTML pages: gulp asset build pipeline