Atom, where can I find syntax sources?

Question

css

Where can I find the syntax sources in the atom, for example, I want to change the standard snippets, add my own regular expression, I searched for 2 hours - I did not find it.
For example, you need jade, stylus or html sources, or where all installed applications are located.
I will be very grateful

Answer 1

searched for 2 hours you apparently are not in google... flight-manual.atom.io/using-atom/sections/snippets
https://www.youtube.com/watch?v=x78SQlvK8Vk