Use of a common css file for a 5 page website

[Larry29936]

I currently have a website that has 5 pages. Each page has it's own css file approximately 4kb in size. They all have different layouts using flexboxes. I'd like to standardize text sizes, padding between elements, etc. by creating one css file which they all look at with individual sections for things like flexbox layouts for each page. Could I do this using id's with classes within the id's? Could I have common settings above the id's?

I tried creating one using all classes but it didn't work. Most pages didn't format correctly.

Thanks in advance for your input.

EDIT: Got them all included in one css file. Tested and working.