Answer: Do not use custom CSS class names for SEO benefits.
Many modern search engines will not be looking for keywords within your tags - imagine the miniscule percentage of websites that actually customize their tags to cater for search engines and how much unnecessary work would be required to implement tag-crawling as a result.
Instead, make sure to use standard tag names such as
ul as much as you can without having to result to CSS tricks. These will make your site much easier to crawl, indexing many more pages as a result. Make sure to use heading tags
(h1, h2 ... hn) as much as possible over custom CSS font tags as search engines will make sure to emphasize these results later.