This is my first question on Stack Overflow, and I would like to ask: is it possible to define different styles for different pages (files) by specifying each file name in CSS, instead of creating a div with 100vh and 100vw?

I want my login and sign-up pages to look different from my other pages. However, if I define styles on the body element for the login and sign-up pages, those styles will also apply to the other pages. Is there a proper or recommended way to handle this?