No, they shouldn't necessarily show the same thing. What if the CSS you are stealing it from is like this:
HTML Code:
<div class="thisclass">
<a class="newcontent_textcontrol" "href="http://www.urlhere.com">button text here</a>
</div>
And you put yours in like this:
HTML Code:
<div class="otherclass">
<a class="new_custom_class" href="http://www.urlhere.com">button text here</a>
</div>
There could be css that is for ".thisclass .newcontent_textcontrol" and unless you also write ".otherclass .new_custom_class" that is exactly the same, then you are going to have different results. These are *cascading* style sheets which means the little <a> that you are writing gets all the CSS from all the classes "above" it also.