The add to cart buttons and sale buttons don't display on certain pages. When I check in the inspector, there are no matched woocommerce CSS rules on those pages.
However the HTML appears to be marked up correctly and the woocommerce.css file is loaded and is loaded after any other stylesheets. The shopping cart page (for example) does use rules from woocommerce.css.
If I switch themes to, say, twenty-twelve, the sale and add to cart buttons appear.
In the problem theme, the text links for add-to-cart work - they are just not styled as buttons.
The test products are all simple and virtual.
Here's a link with no woocommerce CSS matched rules
Here's a link with woocommerce CSS matched rules
I cannot see where the errors lies.