clarify browser polyfills

plugins/css-blank-pseudo/README.md

@@ -5,6 +5,10 @@
 [PostCSS Blank Pseudo] lets you style form elements when they are empty, following 
 the [Selectors Level 4] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 input:blank {
 	background-color: yellow;

plugins/css-blank-pseudo/docs/README.md

@@ -19,6 +19,10 @@
 [<humanReadableName>] lets you style form elements when they are empty, following 
 the [Selectors Level 4] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 <example.css>
 

plugins/css-has-pseudo/README.md

@@ -4,6 +4,10 @@
 
 [PostCSS Has Pseudo] lets you style elements relative to other elements in CSS, following the [Selectors Level 4] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 .title:has(+ p) {
 	margin-bottom: 1.5rem;

plugins/css-has-pseudo/docs/README.md

@@ -18,6 +18,10 @@
 
 [<humanReadableName>] lets you style elements relative to other elements in CSS, following the [Selectors Level 4] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 <example.css>
 

plugins/css-prefers-color-scheme/README.md

@@ -4,6 +4,10 @@
 
 [Prefers Color Scheme] lets you use light and dark color schemes in all browsers, following the [Media Queries] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the media queries
+- add the [browser polyfill](#browser) that triggers specific queries in a browser
+
 ```pcss
 @media (prefers-color-scheme: dark) {
 	:root {

plugins/css-prefers-color-scheme/docs/README.md

@@ -18,6 +18,10 @@
 
 [<humanReadableName>] lets you use light and dark color schemes in all browsers, following the [Media Queries] specification.
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the media queries
+- add the [browser polyfill](#browser) that triggers specific queries in a browser
+
 ```pcss
 <example.css>
 

plugins/postcss-focus-visible/README.md

@@ -5,9 +5,9 @@
 [PostCSS Focus Visible] lets you use the `:focus-visible` pseudo-class in CSS, 
 following the [Selectors Level 4 specification].
 
-It is the companion to the [focus-visible polyfill]. Note that this plugin
-alone **is not** sufficient to polyfill for `:focus-visible` and that you need
-the browser's polyfill as well.
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [focus-visible polyfill] that sets the attribute or class on elements in a browser
 
 [!['Can I use' table](https://caniuse.bitsofco.de/image/css-focus-visible.png)](https://caniuse.com/#feat=css-focus-visible)
 

plugins/postcss-focus-visible/docs/README.md

@@ -19,9 +19,9 @@
 [<humanReadableName>] lets you use the `:focus-visible` pseudo-class in CSS, 
 following the [Selectors Level 4 specification].
 
-It is the companion to the [focus-visible polyfill]. Note that this plugin
-alone **is not** sufficient to polyfill for `:focus-visible` and that you need
-the browser's polyfill as well.
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [focus-visible polyfill] that sets the attribute or class on elements in a browser
 
 [!['Can I use' table](https://caniuse.bitsofco.de/image/css-focus-visible.png)](https://caniuse.com/#feat=css-focus-visible)
 

plugins/postcss-focus-within/README.md

@@ -5,6 +5,10 @@
 [PostCSS Focus Within] lets you use the `:focus-within` pseudo-class in CSS, 
 following the [Selectors Level 4 specification].
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 .my-form-field:focus-within label {
 	background-color: yellow;

plugins/postcss-focus-within/docs/README.md

@@ -19,6 +19,10 @@
 [<humanReadableName>] lets you use the `:focus-within` pseudo-class in CSS, 
 following the [Selectors Level 4 specification].
 
+To use this feature you need to do two things :
+- add the [PostCSS plugin](#usage) that transforms the selector into a class or attribute
+- add the [browser polyfill](#browser) that sets the attribute or class on elements in a browser
+
 ```pcss
 <example.css>