title: Vuetify v-flex width specifications
body: <p>I can't find any proper references for the <code>xs</code>, <code>sm</code>, <code>md</code>, <code>lg</code> and <code>xl</code> directives of <code>v-flex</code> in Vuetify. If I want two columns in extra small layouts, three in small layouts, four in medium layouts, six in large layouts, and 12 in extra-large layouts, then is this the correct HTML?</p>
  
  <pre><code>&lt;v-flex xs2 sm3 md4 lg6 xl12&gt;
      Mostly harmless.
  &lt;/v-flex&gt;
  </code></pre>