CSS: ID doesn't work but Class does : <p>When applying a style to something like an unordered list, why does Class work but Id has no effect. Listo1 displays a bulleted list and Listo2 displays an unbulleted list (at least in the html editors I've tried such as the W3 and Codecademy ones).</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;body&gt;
&lt;style&gt; 

.listo1{
    list-style-type : none;
}

.listo2{
    list-style-type : none;
}

&lt;/style&gt;
&lt;h2&gt;Unordered List without Bullets&lt;/h2&gt;

&lt;ul id="listo1"&gt;
  &lt;li&gt;Coffee&lt;/li&gt;
  &lt;li&gt;Tea&lt;/li&gt;
  &lt;li&gt;Milk&lt;/li&gt;
&lt;/ul&gt;

&lt;ul class="listo2"&gt;
  &lt;li&gt;Coffee&lt;/li&gt;
  &lt;li&gt;Tea&lt;/li&gt;
  &lt;li&gt;Milk&lt;/li&gt;
&lt;/ul&gt;  

&lt;/body&gt;
&lt;/html&gt;
</code></pre>
