Hi,
that's a misuse of the h3 tag in my opinion. It's a header tag and shouldn't really be used to decorate body text.
I think a better structure would be:
<h1>Main page keyword Title
<p>text
<h2>Page sub-title(s)
<p> text
<h3>paragraph titles...
<p> text
However, if you really want to do that you can do it very easily with CSS eg something like (put these somewhere in your <head> tags:
<style>
<!--
h1 {color:black;background-color:white;padding:0px;margin:0px;font-size:15px;text-align:center;font-family:verdana;font-weight:600;text-decoration:none;}
h2 {color:black;background-color:white;padding:0px;margin:0px;font-size:14px;text-align:center;font-family:verdana;font-weight:600;text-decoration:none;}
h3 {color:black;background-color:white;padding:0px;margin:0px;font-size:12px;text-align:center;font-family:verdana;font-weight:400;text-decoration:none;}
p {color:black;background-color:white;padding:0px;margin:0px;font-size:12px;text-align:center;font-family:verdana;font-weight:400;text-decoration:none;}
//-->
</style>
You should offer font alternatives, but I never do, and you can make the code more efficient by h1 h2 h3 {..} etc. but the above layout is easier to read and edit. After you've played a little with the above settings and you are happy, you can experiment with other tags and put the css in an external file.
Cheers,
Paz.