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, 62 insertions, 0 deletions

diff --git a/site/assets/js/color-modes/index.js b/site/assets/js/color-modes/index.js
new file mode 100644
index 000000000..51bfd40a7
--- /dev/null
+++ b/site/assets/js/color-modes/index.js
@@ -0,0 +1,62 @@
+/*!
+ * Color mode toggler for Bootstrap's docs (https://getbootstrap.com/)
+ * Copyright 2011-2022 The Bootstrap Authors
+ * Licensed under the Creative Commons Attribution 3.0 Unported License.
+ */
+
+(() => {
+  'use strict'
+
+  const storedTheme = localStorage.getItem('theme')
+
+  const getPreferredTheme = () => {
+    if (storedTheme) {
+      return storedTheme
+    }
+
+    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'
+  }
+
+  const setTheme = function (theme) {
+    if (theme === 'auto' && window.matchMedia('(prefers-color-scheme: dark)').matches) {
+      document.documentElement.setAttribute('data-bs-theme', 'dark')
+    } else {
+      document.documentElement.setAttribute('data-bs-theme', theme)
+    }
+  }
+
+  setTheme(getPreferredTheme())
+
+  const showActiveTheme = theme => {
+    const activeThemeIcon = document.querySelector('.theme-icon-active use')
+    const btnToActive = document.querySelector(`[data-bs-theme-value="${theme}"]`)
+    const svgOfActiveBtn = btnToActive.querySelector('svg use').getAttribute('href')
+
+    document.querySelectorAll('[data-bs-theme-value]').forEach(element => {
+      element.classList.remove('active')
+    })
+
+    btnToActive.classList.add('active')
+    activeThemeIcon.setAttribute('href', svgOfActiveBtn)
+  }
+
+  window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', () => {
+    if (storedTheme !== 'light' || storedTheme !== 'dark') {
+      setTheme(getPreferredTheme())
+    }
+  })
+
+  window.addEventListener('load', () => {
+    showActiveTheme(getPreferredTheme())
+
+    document.querySelectorAll('[data-bs-theme-value]')
+      .forEach(toggle => {
+        toggle.addEventListener('click', () => {
+          const theme = toggle.getAttribute('data-bs-theme-value')
+          localStorage.setItem('theme', theme)
+          setTheme(theme)
+          showActiveTheme(theme)
+        })
+      })
+  })
+})()