You ARE missing the point. CSS is used for a site's layout/presentation. That and only that with a proper document type, proper use of syntax with the selected doctype and check of all coding errors for CSS/HTML will go a longer way to make your pages cross-browser compatible. NOT JavaScript!!! JS can be used to "sniff" out a browser being used and deliver a CSS file for that browser, but it is unnecessary! JS is dependent on users having it enabled for your site so the CSS file may never be selected.
Choosing Dimensions for Your Web Page Layout:
In Search of the Holy Grail: http://www.alistapart.com/articles/holygrail/
http://www.elated.com/articles/choosing-dimensions-for-your-web-page-layout/
How to create flexible sites quickly using standards like CSS and XHTML: http://www.ibm.com/developerworks/web/library/wa-rapid/
Care With Font Size: http://www.w3.org/QA/Tips/font-size
Websites Shouldn’t Look The Same Across Different Browsers: http://www.noupe.com/design/websites-shouldnt-look-the-same-across-different-browsers%E2%80%A6here-is-why.html
Cross-Browser CSS in Seconds with Prefixr: http://net.tutsplus.com/articles/news/cross-browser-css-in-seconds-with-prefixr/
It’s Not Responsive Web Building, It’s Responsive Web Design: http://www.getfinch.com/finch/entry/its-not-responsive-web-building-its-responsive-web-design/
Beginner’s Guide to Responsive Web Design: http://thinkvitamin.com/design/beginners-guide-to-responsive-web-design/
Why Validate?: http://validator.w3.org/docs/why.html
CSS Validator: http://jigsaw.w3.org/css-validator/
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