 <p>here is very simple solution with a short css display:table</p> <pre><code>&lt;div id="main" class="_dt-no-rows"&gt; &lt;div id="aside" contenteditable="true"&gt; Aside &lt;br&gt; Here's the aside content &lt;/div&gt; &lt;div id="content" contenteditable="true"&gt; Content &lt;br&gt; geht's pellentesque wurscht elementum semper tellus s'guelt Pfourtz !. gal hopla &lt;br&gt; TIP : Just clic on this block to add/remove some text &lt;/div&gt; &lt;/div&gt; </code></pre> <p>here is css</p> <pre><code>#main { display: table; width: 100%; } #aside, #content { display: table-cell; padding: 5px; } #aside { background: none repeat scroll 0 0 #333333; width: 250px; } #content { background: none repeat scroll 0 0 #E69B00; } </code></pre> <p>its look like this </p> <p><img src="https://i.stack.imgur.com/eBmDK.png" alt="enter image description here"></p>