i cant remove underline : <p>bold-normal,italic-normal working but underline-none not working? why?How fix first example with change styles parameters.</p>

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<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;html&gt;
&lt;head&gt;
&lt;meta charset="UTF-8"&gt;
&lt;style type="text/css"&gt;
vurgulu {
  text-decoration: underline;
  font-weight: bold;
  font-style: italic;
  font-size:40;
}
vurgusuz{
  text-decoration: none;
  font-weight: normal;
  font-style: normal;
  font-size:40;
}

&lt;/style&gt;
&lt;/head&gt;
&lt;body&gt;
Why output different? why first ex. zalimi underline?&lt;br&gt;
&lt;vurgulu&gt;Zulmü alkışlayamam, &lt;vurgusuz&gt;zalimi&lt;/vurgusuz&gt; asla sevemem;&lt;/vurgulu&gt;
&lt;br&gt;
&lt;vurgulu&gt;Zulmü alkışlayamam, &lt;/vurgulu&gt;&lt;vurgusuz&gt;zalimi&lt;/vurgusuz&gt;&lt;vurgulu&gt; asla sevemem;&lt;/vurgulu&gt; 
&lt;/body&gt;
&lt;/html&gt;</code></pre>
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