Div style according to the place of CSS : <p>I have the following HTML file:</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;style&gt;
        #aDiv{
            width:300px;
            height:100px;
            background-color:blue;
        }
    &lt;/style&gt;
    &lt;!--link rel="stylesheet" href="style.css"--&gt;
&lt;/head&gt;

&lt;body&gt;
    &lt;div id="aDiv"&gt;&lt;/div&gt;
&lt;/body&gt; 
</code></pre>

<p></p>

<p>If I launch the html in the above form, the blue rectangle is displayed. 
If I saved the style in a css file (respectively <strong><em>style.css</em></strong>) the rectangle is not displayed. This behaviour is valid for all the browsers I tried (Firefox, IE, Chrome). How to solve this problem ?</p>
