Need Regexp for classname replace
<p>Hi
I have following HTML code: 
Its look like</p>

<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;/head&gt;
&lt;style id="styletag"&gt;
.class3{
}
.sec2{
}
.this3{
}
&lt;/style&gt;

&lt;body&gt;
&lt;div class="class1 class2 class3"&gt;content&lt;/div&gt;
&lt;div class="sec1 sec2 sec3"&gt;content2&lt;/div&gt;
&lt;div class="this1 this2 this3"&gt;content2&lt;/div&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>I am having the values class3, sec2 and this3 in array.<br />
I want to replace this class3,sec2 and this3 from the HTML code.<br />
And I also want to remove the style tag entirely (its having the id name 'styletag').</p>

<p>How do i use the regexp?</p>
