Is there a simple reason why my bg image won't appear?

So I’m trying to create some rounded corners at the bottom of a table on my site, and I’m trying to do so by setting a background image for the master table, using CSS.

The site is this:
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http://www.northwesttraildogs.com/

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Is there a simple reason why this isn’t working, or should I just keep banging my head against the wall?

Also for the record, I’m definitely only an amateur website builder, so thanks for any help!