How to make something like float: down with relative position? : <p>I'm trying to move the element to the bottom of its parent but only way to do that is to make it positioned absolute but i want it to be relative.</p>

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<pre class="snippet-code-css lang-css prettyprint-override"><code>#output{
  height: 100px;
  background-color: red;
}

#inner{
  height: 30px;
  background-color: blue;
  /*float: down*/
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="output"&gt;
  &lt;div id="inner"&gt;&lt;/div&gt;
&lt;/div&gt;</code></pre>
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