Before CSS, the appearance of a Web page was dictated by HTML, which had very few visual styling tools, meaning most Web pages were looking simple. For example, here is what www.msn.com looked like in 1996:
And here is what www.msn.com (made with lots of CSS) looks like now!
Before and after CSS
all documents looked very similar – it was difficult for different companies to express their brand identities in documents
possibilities for styling were very limited and style was difficult to control and maintain – style had to be applied to content directly, so you couldn’t update style without having to touch content and vice versa.
Content authors didn’t have to worry about style, they could just focus on content
Content authors didn’t have to worry about what device users would view their document on, those considerations could be handled by the CSS
Style became much more efficient- a single rule could apply to multiple elements and a single style sheet could apply to multiple documents.