Back to That Cascade Thing
So, where does the cascading come in, you might ask? Well, while there are three methods of including CSS in web development, you can use them independently or in combination. The thing to remember is that, while you are including multiple style declarations, they will cascade through until all styles have been applied to those elements. For instance, if you declare that paragraphs should be bolded in your first included style sheet and then duplicate that same paragraph selector in a subsequent style declaration, attaching italic text to the same paragraphs, the latter will not nullify the bold, but rather will add to it, cascading as it goes. Once both style sheet declarations have been loaded, all matching paragraphs will have bold and italicized text.
Additionally, you may wish to have a global style sheet for your entire site that will cascade down through all your pages. By including this site wide, you can then create smaller, more specific style declarations that may be included only on specific sections (or even pages) of your website. Once those styles are in place, you can continue to add more specific selectors and styles knowing that your previous declarations will continue to cascade and not break the overall feel of your site (even across different browsers).
By considering the behavior of CSS and defining additional style declarations, it is very easy to create some intricate cascades that give you precise control over your webpage and can be shared across your entire website. Understanding the cascading principle of CSS and applying it to your own style definitions is key to having a robust, maintainable website.