How can I increase the line-through width?

Can you help with a CSS issue?

http://adts.spidercreations.net/shop/
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Note the regular price on the category page as well as the product page. I'm trying to find a method to increase the thickness of the line-through for the regular price of an item when the sale price is displayed.

I understand it's tied to the font, but I understand there is a way to do it with maybe a border line or something while positioning the line using something called :before?

Tried a few bits of code I found, but it was not working.

Suggestions?