Blogger (blogspot) dynamic CSS class.

layout.xml

<!-- put inside <head/> tag -->
<style>
  <b:loop index='i' values='1 to 100' var='n'>
    <b:if cond='data:n%5 == 0'>
      .w-<data:n/>p {width:<data:n/>%;}
      .h-<data:n/>p {height:<data:n/>%;}
    </b:if>
  </b:loop>
</style>

<!--
usage:
<div class="w-100p"/>
<span class="w-5p">hai</hai>
etc.

live demo in my blog (http://ne-a-r.blogspot.com/)
-->