title: How to properly add divs inside another div so the original design doesn't break?
body: <p>I have a this basic HTML:</p>
  
  <pre><code>&lt;div id="views-container"&gt;
      &lt;div id="html-container"&gt;&lt;/div&gt;
      &lt;div id="original-page-container"&gt;&lt;/div&gt;
      &lt;div id="result-page-container"&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>This is the css for those divs:</p>
  
  <pre><code>#views-container &gt; div{
      height:90%;
      width:33%;
      display:inline-block;
  }
  
  #html-container{
      background-color: pink;
  }
  
  #original-page-container{
      background-color: yellow;
  }
  
  #result-page-container{
      background-color: gray;
  }
  </code></pre>
  
  <p>This is the final output:</p>
  
  <p><img src="https://i.stack.imgur.com/nkBZn.png" alt="enter image description here"></p>
  
  <p>But then I want to add two divs inside </p>
  
  <blockquote>
    <p>html-container</p>
  </blockquote>
  
  <p>, like this:</p>
  
  <pre><code>&lt;div id="views-container"&gt;
      &lt;div id="html-container"&gt;
          &lt;div id="html-content-area"&gt;
              &lt;textarea id="OutputHTML"&gt;&lt;/textarea&gt;
          &lt;/div&gt;
          &lt;div id="html-info-area"&gt;
              bla bla bla
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>when I do this, this is how the page is rendered.</p>
  
  <p><img src="https://i.stack.imgur.com/1IdJq.png" alt="enter image description here"></p>
  
  <p>I want the textarea inside <strong>html-content-area</strong> 
  to use all width and heigth from <strong>html-container</strong>.
  Later, i will need to hide <strong>html-content-area</strong>  in order
  to show something in <strong>html-info-area</strong>.</p>
  
  <p>How could I add those divs inside html-content-area<br>
  so they don't break the original design?</p>
  
  <p>I pasted the code in fiddle:
  <a href="http://fiddle.jshell.net/eyCbB/" rel="nofollow noreferrer">http://fiddle.jshell.net/eyCbB/</a></p>
  
  <p>Thanks in advance!</p>