By definition, CSS is an external document designed to control the look and
feel of web  pages, providing uniformity and the ability to change the look
and feel by changing the style sheet  rather than individual documents. The
only way for a style sheet to affect the rendering of a web page, however,
that I know of, is for the Web page  to include a line in the header
referencing the style sheet.All Web pages  you wish to be so governed must
have this same reference.

It may be possible, however, to use a third party tool to do a search and
replace on a group of files: this would allow you to insert the CSS
reference line in the header of all your Web pages all at once. But if these
documents are checked into SPS, then it would be harder to do that.

The answer to your question in your message - "without specifying it in
every web page" - is NO. You must specify the reference in every Web page.