Flexbox mixed full and half width layout
<p>I have 7 items in a container. How can I make the first 3 be full width and the next 7 be 50% width? </p>

<p>I also need element that are in the same row visually to have the same height. </p>

<p>I can use flexbox for this if necessary. In this demo the container has a fixed width but in reality its a responsive layout so the width varies. </p>

<p><a href="http://codepen.io/anon/pen/yJoPwK" rel="nofollow noreferrer">http://codepen.io/anon/pen/yJoPwK</a></p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-css lang-css prettyprint-override"><code>.cont {
  display: flex;
  flex-direction: column;
  border: 1px solid grey;
  width: 200px;
  margin: auto;
}
.item-1 {
  background: blue;
}
.item-2 {
  background: green;
}
.item-3 {
  background: yellow;
}
.item-4 {
  background: blue;
}
.item-5 {
  background: grey;
}
.item-6 {
  background: orange;
}
.item-7 {
  background: gold;
}
.item-4,
.item-5,
.item-6,
.item-7 {
  width: 50%;
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="cont"&gt;
  &lt;div class="item item-1"&gt;1&lt;/div&gt;
  &lt;div class="item item-2"&gt;2&lt;/div&gt;
  &lt;div class="item item-3"&gt;3&lt;/div&gt;
  &lt;div class="item item-4"&gt;4 &lt;br&gt; wrap&lt;/div&gt;
  &lt;div class="item item-5"&gt;5&lt;/div&gt;
  &lt;div class="item item-6"&gt;6&lt;/div&gt;
  &lt;div class="item item-7"&gt;7&lt;/div&gt;
&lt;/div&gt;</code></pre>
</div>
</div>
</p>

<p>This is the layout im trying to achieve:</p>

<p><a href="https://i.stack.imgur.com/a5Os8.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/a5Os8.jpg" alt="enter image description here"></a></p>