Add dark mode support (#35857)

* Add dark mode to docs

* Minor fix: missing space indentation

* Minor fix: revert utilities/z-index added-in modification

* Remove prev: and next: from doc because extracted to another PR

* Use .bg-body-tertiary in all Utilities > Overflow examples

* fix example

* Fix up spacing examples

* Update box-shadow Sass variables and utilities to auto-adjust to color modes

* Remove unused docs class

* Refactor form styles to use CSS variable for background images on .form-check and .form-switch

* Fix docs selector

* Rename shortcut for clarity

* Heading consistency

* Reintroduce missing 4th grid item in Utilities > Spacing example

* Fix bundlewatch

* .bd-callout* rendering is OK so removing comments in the code

* Update scss/_utilities.scss

Co-authored-by: Julien Déramond <[email protected]>

* Fix gutters example styling

* Fix text colors on background utils docs

* redesign and fix up position marker example, which doesn't show nicely in darkmode but at least isn't broken

* fix some color utils examples

* Deprecate mixin notice

* Deprecate notice for list-group-item-variant() mixin

* Revamp new link CSS vars

* Use map-keys in some each Sass files

* Remove list-group-item-variant mixin ref in sass loop desc

* Display CSS vars scoped to our built-in dark mode

* Revert previous commit

* Fix list group variant link

* Fix typo

* Remove imports of alert/list-group mixins in scss/_mixins.scss

* Small formatting + comments removal in scss/_content.scss

* Fix alert links colors

* fix dropdown border-radius mixin

* fix link color and underline again, this time using CSS var override for color var and fallback value for the underline

* fix colors on docs navbar for dark mode

* remove two changes

* missing ref

* another link underline fix, just use sass vars for link decoration for now

* missing color bg docs, plus move dropdown override to scss

* more changes from review

* fix some examples, drop unused docs navbar styles, update docs navbar color mode to use mixin

* Few fixes around type

- Restored CSS variable for color on headings, this time with a fallback value
- In conjunction, restored and wrapped the default CSS var with a null value check
- Split headings and paragraphs docs in Reboot, elaborated on them

* Restyle custom details > summary element in docs

* Rewrite some migration docs

* fix form checks

* Fix up some navbar styling, tweak docs callout

* Fix select images, mostly for validation styling

* Clean up some migration notes, document some new form control CSS vars, mention new variables-dark in sass docs

* Update site/content/docs/5.2/components/scrollspy.md

Co-authored-by: Julien Déramond <[email protected]>

* Apply suggestions from code review

Co-authored-by: Julien Déramond <[email protected]>

* mention form control css vars in migration guide

* Tweak grid and flex docs background examples

* clarify some docs

* fix some more things

Co-authored-by: Julien Déramond <[email protected]>
Co-authored-by: Julien Déramond <[email protected]>

1 files changed, 10 insertions, 4 deletions

diff --git a/site/content/docs/5.2/components/close-button.md b/site/content/docs/5.2/components/close-button.md
index f4a3ed071..39b80e1cd 100644
--- a/site/content/docs/5.2/components/close-button.md
+++ b/site/content/docs/5.2/components/close-button.md
@@ -22,13 +22,19 @@ Disabled close buttons change their `opacity`. We've also applied `pointer-event
 <button type="button" class="btn-close" disabled aria-label="Close"></button>
 {{< /example >}}
 
-## White variant
+## Dark variant
 
-Change the default `.btn-close` to be white with the `.btn-close-white` class. This class uses the `filter` property to invert the `background-image`.
+{{< callout info >}}
+**Heads up!** As of v5.3.0, the `.btn-close-white` class is deprecated. Instead, use `data-bs-theme="dark"` to change the color mode of the close button.
+{{< /callout >}}
+
+Add `data-bs-theme="dark"` to the `.btn-close`, or to its parent element, to invert the close button. This uses the `filter` property to invert the `background-image` without overriding its value.
 
 {{< example class="bg-dark" >}}
-<button type="button" class="btn-close btn-close-white" aria-label="Close"></button>
-<button type="button" class="btn-close btn-close-white" disabled aria-label="Close"></button>
+<div data-bs-theme="dark">
+  <button type="button" class="btn-close" aria-label="Close"></button>
+  <button type="button" class="btn-close" disabled aria-label="Close"></button>
+</div>
 {{< /example >}}
 
 ## Sass