title: Vue multiselect show always behind Bootstrap input groups
body: <p>I'm having a really hard time with this.
  I'm using <a href="http://monterail.github.io/vue-multiselect/" rel="nofollow noreferrer">Vue Multiselect</a> and Bootstrap's 3 Input Groups.</p>
  
  <p>The problem here is that the multiselect options show behind the input group no matter what z-index I use on it. I know that I can change input group z-index to 0, but watching Bootstrap SASS files it says: "Ensure that the input is always above the <em>appended</em> addon button for proper border colors" so I don't know if it is safe to do this:</p>
  
  <pre><code>.input-group .form-control {
      z-index: 0;
  }
  </code></pre>
  
  <p>I tried every selector on the multiselect but none makes effect. Any help would be appreciated.
  Here is the fiddle: <a href="https://jsfiddle.net/cristiancastrodc/c9gdxg3s/" rel="nofollow noreferrer">https://jsfiddle.net/cristiancastrodc/c9gdxg3s/</a></p>