Why is CSS good for Google

Cascading Style Sheets (CSS) are used to separate the stylistic elements of a page such as layout, colour and fonts from the content of the page such as paragraphs and images.

So why is CSS good for Google?

■ CSS allows for small file sizes
■ CSS allows you greater control of page structure
■ CSS allows you to hide certain content from browsers while it will still be visible by Google

By taking styles out of the HTML page and putting it into a standalone style sheet (.css file), you can reduce the overall amount of code in your web pages. Pages with little code have smaller file sizes and Google prefers pages with small file sizes (many other search engines do too).
Though Google doesn't offer specific advice on this matter, the search engine optimisation community is generally agreed that 100KB is a good upper limit for page sizes.

■ CSS allows you to structure your website according to HTML standards without changing the look-and-feel of the page.

Google rewards pages that are well structured, though many designers choose to ignore standards and guidelines as much as possible, because they (incorrectly) believe standards lead to bland pages.
Using CSS you can hide content from certain browsers in certain situations. For example you may have some content that you only want to appear in print, or you may want certain content to only be shown on screen and not in print (such as page navigation). The advantage is that Google will still index all of the content and you will still get the benefit that content brings.

Browser Compatibility
Different browsers still interpret CSS standards in different ways, while some very old browsers don't read CSS at all. Ensure that your CSS is as cross-browser compatible as possible, and that your HTML pages look acceptable even without CSS.