Most web design companies author web page with the rules how content and images are presented on the same page. This will create issues like slow web page download, less cross browser compatibility, huge website size with higher hosting cost, not suitable for handheld devices, printing problems and many more.
Rather than repeating presentation rules and elements like images on all pages we can separate the entire presentation rules of a website in a single style sheet. The key advantages are listed below:
The content has been freed up. It can be presented in a lot of different ways for different users.
Web pages will be very simple and less likely to create errors when modifying them.
It will be easier to maintain the website because of simple code and use of single style sheet across the website.
Once the browser has automatically downloaded the style sheet when it accesses the first page, the subsequent pages will download very quickly because the browser stores a copy of the style sheet.