CSS top not working : <p>i have this code html.</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;title&gt;e-Rario&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;div style="height: 60px; background: blue;"&gt;
        &lt;div style="top: 25%; background: green;"&gt;e-Rario&lt;/div&gt;
    &lt;/div&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>Why is the top property nor working?</p>
