Improve background note

_rules/important-letter-spacing-wide-enough-24afc2.md

@@ -55,9 +55,9 @@ While some assistive technologies are able to set [user origin][] or [user agent
 
 ## Background
 
-When a style is [declared][] in the `style` attribute with an [important][] declaration, it "wins" the [cascade sort] over any other style from [author origin][], i.e. it cannot be overridden by any of these. On the other hand, if such a style is [declared][] in a style sheet, it can still "lose" the [cascade sort][] to declarations with higher [specificity][] or simply coming from a later style sheet (such as ones injected by assistive technologies). This rule ensures that the element is not in the first case and that the style can be overridden by users, unless it is already at least the minimum required threshold. [Important][] styles that are declared with the [user][user origin] or [user agent][user agent origin] origin can win the [cascade sort][] over styles with the [author origin][].
+Styles [declared][] in a `style` attribute have higher [cascade specificity][] than any selector; therefore, they "win" the [cascade sort] over any other style from [author origin][], i.e. it cannot be overridden by any of these. On the other hand, if such a style is [declared][] in a style sheet, it can still "lose" the [cascade sort][] to declarations with higher [specificity][] or simply coming from a later style sheet (such as ones injected by assistive technologies). This rule ensures that the element is not in the first case and that the style can be overridden by users, unless it is already at least the minimum required threshold. [Important][] styles that are declared with the [user][user origin] or [user agent][user agent origin] can win the [cascade sort][] over styles with the [author origin][].
 
-CSS specifications define each declaration as being either [important][] (if it has the `!important` annotation) or [normal][]. Given that `normal` is also a keyword for this property, and that `!important` is wider known that this distinction, this rule rather uses "[important][]"/"not [important][]" to avoid confusion.
+CSS specifications define each declaration as being either [important][] (if it has the `!important` annotation) or [normal][]. Given that `normal` is also a keyword for some properties, and that `!important` is wider known that this distinction, this rule rather uses "[important][]"/"not [important][]" to avoid confusion.
 
 ### Bibliography
 
@@ -293,6 +293,7 @@ The [computed][] value of the `letter-spacing` property of this text node is the
 
 [author origin]: https://www.w3.org/TR/css-cascade-4/#cascade-origin-author 'CSS Cascading and Inheritance Level 4 (Working draft) - Cascading Origins - Author Origin'
 [cascade sort]: https://www.w3.org/TR/css-cascade-4/#cascade-sort 'CSS Cascading and Inheritance Level 4 (Working draft) - Cascade Sort'
+[cascade specificity]: https://www.w3.org/TR/css-cascade-3/#cascade-specificity 'CSS Cascading and Inheritance Level 4 (Candidate Recommendation) - Cascade specificity'
 [computed]: https://www.w3.org/TR/css-cascade-4/#computed 'CSS Cascading and Inheritance Level 4 (Working draft) - Computed Values'
 [declared]: https://www.w3.org/TR/css-cascade-4/#declared 'CSS Cascading and Inheritance Level 4 (Working draft) - Declared Values'
 [html element]: #namespaced-element
@@ -303,6 +304,7 @@ The [computed][] value of the `letter-spacing` property of this text node is the
 [sc148]: https://www.w3.org/TR/WCAG21/#visual-presentation 'Success Criterion 1.4.8 Visual Presentation'
 [specified]: https://www.w3.org/TR/css-cascade-4/#specified 'CSS Cascading and Inheritance Level 4 (Working draft) - Specified Values'
 [specificity]: https://www.w3.org/TR/selectors/#specificity 'CSS Selectors Level 4 (Working draft) - Specificity'
+[text node]: https://dom.spec.whatwg.org/#text
 [user origin]: https://www.w3.org/TR/css-cascade-4/#cascade-origin-user 'CSS Cascading and Inheritance Level 4 (Working draft) - Cascading Origins - User Origin'
 [user agent origin]: https://www.w3.org/TR/css-cascade-4/#cascade-origin-ua 'CSS Cascading and Inheritance Level 4 (Working draft) - Cascading Origins - User Agent Origin'
 [visible]: #visible 'Definition of visible'