title: How to use Bootstrap 4 media breakpoints in SASS?
body: <p>On the official <a href="https://v4-alpha.getbootstrap.com/layout/overview/" rel="noreferrer">bootstrap website</a> it says:</p>
  
  <blockquote>
    <p>Since we write our source CSS in Sass, all our media queries are
    available via Sass mixins:</p>
  </blockquote>
  
  <pre><code>@include media-breakpoint-up(xs) { ... }
  @include media-breakpoint-up(sm) { ... }
  @include media-breakpoint-up(md) { ... }
  @include media-breakpoint-up(lg) { ... }
  @include media-breakpoint-up(xl) { ... }
  
  // Example usage:
  @include media-breakpoint-up(sm) {
    .some-class {
      display: block;
    }
  }
  </code></pre>
  
  <p>Now, I am using SASS for my CSS, and I am also using Bootstrap, but I am combining the two only by including them in the HTML.</p>
  
  <p>When i try to do something like this in my SASS file: </p>
  
  <pre><code>@include media-breakpoint-up(xl) { ... }
  </code></pre>
  
  <p>I get an error:</p>
  
  <blockquote>
    <p>Undefined Mixin</p>
  </blockquote>
  
  <p>I guess that this is because my SASS file does not know about Bootstrap, since I only include the Bootstrap in the HTML.</p>
  
  <p>How can I include Bootstrap 4 into my SASS file, as a partial? (I guess that this is what I have to do...)</p>
  
  <p>PS: I am using Bootstrap 4, and I would prefer a solution that does not require Bower or RubyGems etc. but just to download the Bootstrap file and include it into my SASS the old-fashioned way - if that is possible at all?</p>