CSS not working for one class (documents attached)

My webpage does not respond to a class named .topic in my CSS. I'm applying .topic to four <td> tags in my webpage. Here is the formatting in .topic.

.topic {font-variant: small-caps;
        text-align: center;}        

This doesn't work. But if I embed .topic in the head of my webpage as shown below, the formatting works.

<style type="text/css">
.topic {font-variant: small-caps;
        text-align: center;}        
</style>

 If you copy the .topic formatiing from the CSS and paste it between <style type="text/css"> and </style>,  you'll see what I'm talking about. Why does .topic work as an embedded style but not from an external style sheet?
stylesheet.css
aSurgery.htm