Backport #31689

docs: fix a few redirects

* Fix GitHub's permanent redirects

* Fix a11yproject redirects

6 files changed, 7 insertions, 7 deletions

diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 2519be0d82..0704e3b2f0 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -216,7 +216,7 @@ includes code changes) and under the terms of the
 [Adhere to the Code Guide.](https://codeguide.co/#css)
 
 - When feasible, default color palettes should comply with [WCAG color contrast guidelines](https://www.w3.org/TR/WCAG20/#visual-audio-contrast).
-- Except in rare cases, don't remove default `:focus` styles (via e.g. `outline: none;`) without providing alternative styles. See [this A11Y Project post](https://a11yproject.com/posts/never-remove-css-outlines/) for more details.
+- Except in rare cases, don't remove default `:focus` styles (via e.g. `outline: none;`) without providing alternative styles. See [this A11Y Project post](https://www.a11yproject.com/posts/2013-01-25-never-remove-css-outlines/) for more details.
 
 ### JS
 
diff --git a/README.md b/README.md
index 3497963114..090ee53a01 100644
--- a/README.md
+++ b/README.md
@@ -63,8 +63,8 @@ Read the [Getting started page](https://getbootstrap.com/docs/4.5/getting-starte
 [![peerDependencies Status](https://img.shields.io/david/peer/twbs/bootstrap)](https://david-dm.org/twbs/bootstrap?type=peer)
 [![devDependency Status](https://img.shields.io/david/dev/twbs/bootstrap)](https://david-dm.org/twbs/bootstrap?type=dev)
 [![Coverage Status](https://img.shields.io/coveralls/github/twbs/bootstrap/v4-dev)](https://coveralls.io/github/twbs/bootstrap?branch=v4-dev)
-[![CSS gzip size](https://img.badgesize.io/twbs/bootstrap/v4-dev/dist/css/bootstrap.min.css?compression=gzip&label=CSS%20gzip%20size)](https://github.com/twbs/bootstrap/tree/v4-dev/dist/css/bootstrap.min.css)
-[![JS gzip size](https://img.badgesize.io/twbs/bootstrap/v4-dev/dist/js/bootstrap.min.js?compression=gzip&label=JS%20gzip%20size)](https://github.com/twbs/bootstrap/tree/v4-dev/dist/js/bootstrap.min.js)
+[![CSS gzip size](https://img.badgesize.io/twbs/bootstrap/v4-dev/dist/css/bootstrap.min.css?compression=gzip&label=CSS%20gzip%20size)](https://github.com/twbs/bootstrap/blob/v4-dev/dist/css/bootstrap.min.css)
+[![JS gzip size](https://img.badgesize.io/twbs/bootstrap/v4-dev/dist/js/bootstrap.min.js?compression=gzip&label=JS%20gzip%20size)](https://github.com/twbs/bootstrap/blob/v4-dev/dist/js/bootstrap.min.js)
 [![BrowserStack Status](https://www.browserstack.com/automate/badge.svg?badge_key=SkxZcStBeExEdVJqQ2hWYnlWckpkNmNEY213SFp6WHFETWk2bGFuY3pCbz0tLXhqbHJsVlZhQnRBdEpod3NLSDMzaHc9PQ==--3d0b75245708616eb93113221beece33e680b229)](https://www.browserstack.com/automate/public-build/SkxZcStBeExEdVJqQ2hWYnlWckpkNmNEY213SFp6WHFETWk2bGFuY3pCbz0tLXhqbHJsVlZhQnRBdEpod3NLSDMzaHc9PQ==--3d0b75245708616eb93113221beece33e680b229)
 [![Backers on Open Collective](https://img.shields.io/opencollective/backers/bootstrap)](#backers)
 [![Sponsors on Open Collective](https://img.shields.io/opencollective/sponsors/bootstrap)](#sponsors)
diff --git a/scss/mixins/_screen-reader.scss b/scss/mixins/_screen-reader.scss
index 21230390eb..6913442b83 100644
--- a/scss/mixins/_screen-reader.scss
+++ b/scss/mixins/_screen-reader.scss
@@ -1,6 +1,6 @@
 // Only display content to screen readers
 //
-// See: https://a11yproject.com/posts/how-to-hide-content/
+// See: https://www.a11yproject.com/posts/2013-01-11-how-to-hide-content/
 // See: https://hugogiraudel.com/2016/10/13/css-hide-and-seek/
 
 @mixin sr-only() {
diff --git a/site/_layouts/docs.html b/site/_layouts/docs.html
index 08788a2547..10c9fcb0c5 100644
--- a/site/_layouts/docs.html
+++ b/site/_layouts/docs.html
@@ -22,7 +22,7 @@
 
         <main class="col-md-9 col-xl-8 py-md-3 pl-md-5 bd-content" role="main">
           <div class="d-md-flex flex-md-row-reverse align-items-center justify-content-between">
-            <a class="btn btn-sm btn-bd-light my-2 my-md-0" href="{{ site.repo }}/tree/v4-dev/site/{{ page.path }}" title="View and edit this file on GitHub" target="_blank" rel="noopener">View on GitHub</a>
+            <a class="btn btn-sm btn-bd-light my-2 my-md-0" href="{{ site.repo }}/blob/v4-dev/site/{{ page.path }}" title="View and edit this file on GitHub" target="_blank" rel="noopener">View on GitHub</a>
             <h1 class="bd-title" id="content">{{ page.title | smartify }}</h1>
           </div>
           <p class="bd-lead">{{ page.description | smartify }}</p>
diff --git a/site/docs/4.5/getting-started/accessibility.md b/site/docs/4.5/getting-started/accessibility.md
index edfe914dff..8f78112b71 100644
--- a/site/docs/4.5/getting-started/accessibility.md
+++ b/site/docs/4.5/getting-started/accessibility.md
@@ -50,7 +50,7 @@ Bootstrap includes support for the [`prefers-reduced-motion` media feature](http
 ## Additional resources
 
 - [Web Content Accessibility Guidelines (WCAG) 2.0](https://www.w3.org/TR/WCAG20/)
-- [The A11Y Project](https://a11yproject.com/)
+- [The A11Y Project](https://www.a11yproject.com/)
 - [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
 - [Tenon.io Accessibility Checker](https://tenon.io/)
 - [Colour Contrast Analyser (CCA)](https://developer.paciellogroup.com/resources/contrastanalyser/)
diff --git a/site/docs/4.5/getting-started/webpack.md b/site/docs/4.5/getting-started/webpack.md
index 0cde33d7a1..f58e434d6e 100644
--- a/site/docs/4.5/getting-started/webpack.md
+++ b/site/docs/4.5/getting-started/webpack.md
@@ -43,7 +43,7 @@ First, create your own `_custom.scss` and use it to override the [built-in custo
 @import "~bootstrap/scss/bootstrap";
 {% endhighlight %}
 
-For Bootstrap to compile, make sure you install and use the required loaders: [sass-loader](https://github.com/webpack-contrib/sass-loader), [postcss-loader](https://github.com/postcss/postcss-loader) with [Autoprefixer](https://github.com/postcss/autoprefixer#webpack). With minimal setup, your webpack config should include this rule or similar:
+For Bootstrap to compile, make sure you install and use the required loaders: [sass-loader](https://github.com/webpack-contrib/sass-loader), [postcss-loader](https://github.com/webpack-contrib/postcss-loader) with [Autoprefixer](https://github.com/postcss/autoprefixer#webpack). With minimal setup, your webpack config should include this rule or similar:
 
 {% highlight js %}
 ...