File extension not registered (I guess...)

[eberkowitz]

Hey, I’m new at coding so I apologize for the bad explanations of what’s going on.
Pretty much, Sublime Text (3) is not registering the extension name on my files, so if I save style.css it’ll open it as html every single time I open the file and I have to manually switch it back every time - kind of a pain. Is there a way to have the default syntax reset to default? And I’m pretty bad at using the preferences so far so some explanation would be awesome! Thanks!