title: Lazyload background-image with lazysizes
body: <p>I want to load a background-image "lazy" with the library <a href="http://afarkas.github.io/lazysizes/" rel="noreferrer">http://afarkas.github.io/lazysizes/</a><br>
  They do mention that the loading of "anything" lazily is possible. But the whole documentation on that is that one:</p>
  
  <pre><code>&lt;div data-ride="carousel" data-script="assets/js/bootstrap.min.js" class="carousel lazyload"&gt;
      &lt;!-- widget content --&gt;
  &lt;div&gt;
  </code></pre>
  
  <p>And I don't get how I could use that for a background-image. Does anybody have experience there on that?</p>