diff --git a/docs/4.0/components/forms.md b/docs/4.0/components/forms.md
index c8e0f2bd7..1fe14ba19 100644
--- a/docs/4.0/components/forms.md
+++ b/docs/4.0/components/forms.md
@@ -1004,8 +1004,8 @@ Here's how it works:
 
 - We wrap the `<input>` in a `<label>` so the custom control properly triggers the file browser.
 - We hide the default file `<input>` via `opacity`.
-- We use `:after` to generate a custom background and directive (*Choose file...*).
-- We use `:before` to generate and position the *Browse* button.
+- We use `::after` to generate a custom background and directive (*Choose file...*).
+- We use `::before` to generate and position the *Browse* button.
 - We declare a `height` on the `<input>` for proper spacing for surrounding content.
 
 In other words, it's an entirely custom element, all generated via CSS.
diff --git a/docs/4.0/content/reboot.md b/docs/4.0/content/reboot.md
index 6fa38a381..f69d2519e 100644
--- a/docs/4.0/content/reboot.md
+++ b/docs/4.0/content/reboot.md
@@ -22,7 +22,7 @@ Here are our guidelines and reasons for choosing what to override in Reboot:
 
 The `<html>` and `<body>` elements are updated to provide better page-wide defaults. More specifically:
 
-- The `box-sizing` is globally set on every element—including `*:before` and `*:after`, to `border-box`. This ensures that the declared width of element is never exceeded due to padding or border.
+- The `box-sizing` is globally set on every element—including `*::before` and `*::after`, to `border-box`. This ensures that the declared width of element is never exceeded due to padding or border.
   - No base `font-size` is declared on the `<html>`, but `16px` is assumed (the browser default). `font-size: 1rem` is applied on the `<body>` for easy responsive type-scaling via media queries while respecting user preferences and ensuring a more accessible approach.
 - The `<body>` also sets a global `font-family`, `line-height`, and `text-align`. This is inherited later by some form elements to prevent font inconsistencies.
 - For safety, the `<body>` has a declared `background-color`, defaulting to `#fff`.
diff --git a/docs/4.0/examples/blog/blog.css b/docs/4.0/examples/blog/blog.css
index 5fed56424..18db4290e 100644
--- a/docs/4.0/examples/blog/blog.css
+++ b/docs/4.0/examples/blog/blog.css
@@ -62,7 +62,7 @@ h6, .h6 {
 .nav-link.active {
   color: #fff;
 }
-.nav-link.active:after {
+.nav-link.active::after {
   position: absolute;
   bottom: 0;
   left: 50%;
diff --git a/docs/4.0/getting-started/introduction.md b/docs/4.0/getting-started/introduction.md
index 08dd83209..4035ae8f4 100644
--- a/docs/4.0/getting-started/introduction.md
+++ b/docs/4.0/getting-started/introduction.md
@@ -97,7 +97,7 @@ On the rare occasion you need to override it, use something like the following:
 }
 {% endhighlight %}
 
-With the above snippet, nested elements—including generated content via `:before` and `:after`—will all inherit the specified `box-sizing` for that `.selector-for-some-widget`.
+With the above snippet, nested elements—including generated content via `::before` and `::after`—will all inherit the specified `box-sizing` for that `.selector-for-some-widget`.
 
 Learn more about [box model and sizing at CSS Tricks](https://css-tricks.com/box-sizing/).
 
diff --git a/docs/4.0/getting-started/options.md b/docs/4.0/getting-started/options.md
index 0b83c47f8..2547ef1ad 100644
--- a/docs/4.0/getting-started/options.md
+++ b/docs/4.0/getting-started/options.md
@@ -46,11 +46,11 @@ All colors available in Bootstrap 4, available as Sass variables and a Sass map
 
 <div class="row">
   {% for color in site.data.colors %}
+    {% unless color.name == "white" or color.name == "gray" or color.name == "gray-dark" %}
     <div class="col-md-4">
-      {% unless color.name == "white" or color.name == "gray" or color.name == "gray-dark" %}
         <div class="p-3 mb-3 swatch-{{ color.name }}">{{ color.name | capitalize }}</div>
-      {% endunless %}
     </div>
+    {% endunless %}
   {% endfor %}
 </div>
 
diff --git a/docs/4.0/migration.md b/docs/4.0/migration.md
index 6c1bf14fc..5a63988cb 100644
--- a/docs/4.0/migration.md
+++ b/docs/4.0/migration.md
@@ -219,6 +219,10 @@ Dropped entirely for the new card component.
 - `.panel-footer` to `.card-footer`
 - `.panel-primary`, `.panel-success`, `.panel-info`, `.panel-warning`, and `.panel-danger` have been dropped for `.bg-`, `.text-`, and `.border` utilities generated from our `$theme-colors` Sass map.
 
+### Progress
+
+- Replaced contextual `.progress-bar-*` classes with `.bg-*` utilities. For example, `class="progress-bar progress-bar-danger"` becomes `class="progress-bar bg-danger"`.
+
 ### Carousel
 
 - Overhauled the entire component to simplify design and styling. We have fewer styles for you to override, new indicators, and new icons.
diff --git a/scss/utilities/_borders.scss b/scss/utilities/_borders.scss
index b7e91c260..3ff603c32 100644
--- a/scss/utilities/_borders.scss
+++ b/scss/utilities/_borders.scss
@@ -44,9 +44,9 @@
 }
 
 .rounded-circle {
-  border-radius: 50%;
+  border-radius: 50% !important;
 }
 
 .rounded-0 {
-  border-radius: 0;
+  border-radius: 0 !important;
 }
