title: CSS floating block resize change into new line
body: <p>How can I create the effect of right hand side with only CSS when block A resize? Block C and sidebar is floating element, when I resize the block A, I hope that block C will move bellow the block A
  <a href="https://jsfiddle.net/1va5xaz8/" rel="nofollow noreferrer">https://jsfiddle.net/1va5xaz8/</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>.sidebar,.c{
   float:left;
  }
  /* Block a will be resize*/
  .a{ 
   width:100px;
   height:100px;
   background:blue;
   margin:10px;
  }
  
  .b{
   width:100px;
   height:300px;
   background:blue;
   margin:10px;
  }
  
  .c{
   width:500px;
   height:100px;
   background:blue;
   margin:10px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="sidebar"&gt;
   &lt;div class="a"&gt;a&lt;/div&gt;
      &lt;div class="b"&gt;b&lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="c"&gt;c&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p><a href="https://i.stack.imgur.com/R62th.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/R62th.png" alt="Example"></a></p>