What is CSS? CSS stands for Cascading Style Sheets. CSS is used by developers to define the look and feel of webpages. Using CSS, developers can modify the colors, font, and sizes of all the content of a webpage. These style sheets are referenced by the HTML document and applied based on conditions set by the developer. Multiple sheets can be referenced throughout the page, hence the name “Cascading,” and it’s generally a methodology that most developers exercise. As with HTML, CSS has a progressive cycle of it’s own, CSS1, CSS2, and CSS3. Here’s an example of posted on W3Schools.
As you can see above, the text sets instruction for background color of the body, header color, font and font size for the paragraph. For further information on CSS, check out the W3 schools link above, and/or feel free to read this helpful article I found at About Tech.