Improve gradients

- Use a semitransparent gradient from light to dark which works on any background-color
- Store the gradient as a custom property (--bs-gradient)
- Remove `.bg-gradient-*` variants in favour of `.bg-gradient` which works even when `$enable-gradients` are enabled
- Add gradients to navbar, active page links and badges when gradients are enabled

site/content/docs/5.0/migration.md

@@ -46,6 +46,8 @@ Changes to our source Sass files and compiled CSS.
 - `color-yiq()` function and related variables are renamed to `color-contrast()` since it's not related to YIQ colorspace anymore. [See #30168.](https://github.com/twbs/bootstrap/pull/30168/)
   - `$yiq-contrasted-threshold` is renamed `$min-contrast-ratio`.
   - `$yiq-text-dark` and `$yiq-text-light` are respectively renamed `$color-contrast-dark` and `$color-contrast-light`.
+- Linear gradients are simplified when gradients are enabled and therefore, `gradient-bg()` now only accepts an optional `$color` parameter.
+- `bg-gradient-variant()` mixin is removed since the `.bg-gradient` class can now be used to add gradients to elements instead of the `.bg-gradient-*` classes.
 
 ## JavaScript
 

site/content/docs/5.0/utilities/colors.md

@@ -39,12 +39,14 @@ Similar to the contextual text color classes, easily set the background of an el
 
 ## Background gradient
 
-When `$enable-gradients` is set to `true` (default is `false`), you can use `.bg-gradient-` utility classes. [Learn about our Sass options]({{< docsref "/customize/sass" >}}) to enable these classes and more.
+By adding a `.bg-gradient` class, a linear gradient is added as background image to the backgrounds. This gradient starts with a semi-transparent white which fades out to the bottom.
+
+Do you need a gradient in your custom CSS? Just add `background-image: var(--bs-gradient);`.
 
 {{< markdown >}}
 {{< colors.inline >}}
 {{- range (index $.Site.Data "theme-colors") }}
-- `.bg-gradient-{{ .name }}`
+<div class="p-3 mb-2 bg-{{ .name }} bg-gradient {{ if or (eq .name "light") (eq .name "warning") }}text-dark{{ else }}text-white{{ end }}">.bg-{{ .name }}.bg-gradient</div>
 {{- end -}}
 {{< /colors.inline >}}
 {{< /markdown >}}