fix(curriculum): 'Adjust the Tone of a Color' test assertion (#46018)

* Fix: 'Adjust the Tone of a Color' test assrtion

* Clarify use of rgb instead of hsl value in test

curriculum/challenges/english/01-responsive-web-design/applied-visual-design/adjust-the-tone-of-a-color.md

@@ -20,9 +20,11 @@ All elements have a default `background-color` of `transparent`. Our `nav` eleme
 The `nav` element should have a `background-color` of the adjusted cyan tone using the `hsl()` property.
 
 ```js
-assert(
-  code.match(/nav\s*?{\s*?background-color:\s*?hsl\(180,\s*?80%,\s*?25%\)/gi)
-);
+// Computed style of hsl(180, 80%, 25%) results in rgb(13,115,115)
+assert.equal(
+  new __helpers.CSSHelp(document).getStyle('nav').getPropVal('background-color', true), 
+  'rgb(13,115,115)'
+)
 ```
 
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