CSS or Cascading Style Sheets. Style sheets give you huge control over your design, and with a few small changes, you could change the look of your whole site. They are added between <head> and </head> tags in the HTML as this:
<link rel="stylesheet" href="/css/styles.css">
You can also add CSS inline within a page, but this is not recommended.
CSS style sheet files have the .css file extension.
Last Revised: 2015-07-01