Websites of any size and complexity can benefit from the use of CSS (Cascading Style Sheets). By using CSS, specifically external CSS files, our clients’ websites are more efficient in the following ways: 

Speed and Performance
Defining all site styles in an external CSS file greatly increases website performance. All modern browsers will download the CSS file and cache it for later use, meaning the entire site’s style sheet only needs to be downloaded once to be used for many site visits. This also decreases the size of each webpage. For those users whose browsers support Gzip or Deflate compression; even further performance could be noticed by compressing the stylesheet.

Manageability
Most websites consist of visuals that are repeated throughout the web experience. CSS allows a developer to name a specific element style and re-use that definition throughout the website. This makes it very easy to change the look of an entire website in a short period of time, with only few changes needed.

Standards Compliancy
Properly using CSS allows a website to validate against a CSS validator, creating a “valid” style sheet. Websites with “valid” style sheets are more likely to work correctly across multiple browsers, maintaining a cohesive look.