Whenever possible, use class and ID names that are semantically meaningful and search-friendly. For example:
<style type="text/css">
<!--
.box {border:1px solid #000;}
.bio h2, .bio h3 {color: #c00;background:#0cc;}
.testimonial h2, .testimonial h3 {color: #0c0; background:#c0c;}
--></style></head><body>
<div class="box bio">
<h2>Our Staff Bios</h2>
<div>
<h3>Barack Obama</h3>
<p>Senator Obama ran for president in 2008...</p>
<h3>Albert Gore</h3>
<p>Vice President Gore raised awareness of global warming ...</p>
</div>
</div>
<div class="box testimonial">...</div>This way, you need to change only the class name in the div, which uses multiple classes, to achieve a different look. The bio class would have one look and the testimonial class would have another.