Update link for Additional Resource section (#28191)

The link to blog article for 'The cascade' was inaccessible, updating with a working link from the same author

foundations/html_css/css-foundations/the-cascade.md

@@ -227,7 +227,7 @@ The following questions are an opportunity to reflect on key topics in this less
 
 This section contains helpful links to related content. It isn't required, so consider it supplemental.
 
-- [The CSS Cascade](https://wattenberger.com/blog/css-cascade) is a great, interactive read that goes a little more in detail about other factors that affect what CSS rules actually end up being applied.
+- [The CSS Cascade](https://2019.wattenberger.com/blog/css-cascade) is a great, interactive read that goes a little more in detail about other factors that affect what CSS rules actually end up being applied.
 - [CSS Specificity Explained](https://www.youtube.com/watch?v=c0kfcP_nD9E) from Kevin Powell goes through various specificity examples and gives some advice on avoiding wrestling with specificity.
 - [CSS Specificity Calculator](https://specificity.keegan.st/) allows you to fill in your own selectors and have their specificity calculated and visualized.
 - [Mozilla CSS Properties Reference](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Properties_Reference) can be used to learn if a particular CSS property is inherited or not; look for the **Inherited** field inside the **Formal Definition** section. Here's an example for [the CSS `color` property](https://developer.mozilla.org/en-US/docs/Web/CSS/color#formal_definition).