title: Grid columns using flexbox with fixed size margin gutters
body: <p>Is it possible to apply a fixed margin (e.g. 5px) to a cell in a flexbox layout, where the row space is evenly distributed among its columns?</p>
  
  <p>Want I want to achieve:</p>
  
  <p><a href="https://i.stack.imgur.com/4RT2P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4RT2P.png" alt="this is the desired layout"></a></p>
  
  <p>My current CSS will only align 3 columns in one row:</p>
  
  <p><a href="http://jsfiddle.net/fm4v13jc/1/" rel="nofollow noreferrer">JSFiddle</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.row {
      display: flex;
      flex-flow: row wrap;
   box-shadow: 0 0 0 1px green;
  }
  
  .col {
      flex: 0 0 25%;
      text-align: center;
   box-shadow: 0 0 0 1px blue;
      background-color: steelblue;
   
   margin: 5px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="row"&gt;
      &lt;div class="col"&gt;
    &lt;div class="panel"&gt;1&lt;/div&gt;
   &lt;/div&gt;
      &lt;div class="col"&gt;
    &lt;div class="panel"&gt;2&lt;/div&gt;
   &lt;/div&gt;
      &lt;div class="col"&gt;
    &lt;div class="panel"&gt;3&lt;/div&gt;
   &lt;/div&gt;
      &lt;div class="col"&gt;
    &lt;div class="panel"&gt;4&lt;/div&gt;
   &lt;/div&gt;
   &lt;div class="col"&gt;&lt;div class="panel"&gt;5&lt;/div&gt;&lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>