The Doubter wrote: where did you find ".hikashop_product_characteristics label" and "@media"?
Did you read my first response here? And the documentation under the link I gave you? The link is also giving you an example for Firebug.
So, it's part of standard, very basic web development. And yes, it can be found/simulated with a browser console as included with at least most browsers.
Again, there's a ton of stuff on CSS and else on the web, and it's worth learning, also because this is more of a support forum for HikaShop and less of a forum for generic web design or specific customizations...