Transition outline-color (#15690)

This PR adds `outline-color` to the transition-property again, and
updates the implementation for `outline-hidden`.

The `outline-hidden` will behave exactly the same as `outline-none`
_except_ in forced colors mode. In forced colors mode, `outline-hidden`
will force a 2px solid border.

Closes: #15591

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Add new `@variant` directive for applying variants to your CSS ([#15663](https://github.com/tailwindlabs/tailwindcss/pull/15663))
+- Include `outline-color` when transitioning colors ([#15690](https://github.com/tailwindlabs/tailwindcss/pull/15690))
 
 ### Fixed
 
@@ -27,6 +28,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Use more modern `--alpha(color / 50%)` syntax instead of `--alpha(color, 50%)` ([#15665](https://github.com/tailwindlabs/tailwindcss/pull/15665))
 - Rename `@variant` to `@custom-variant` ([#15663](https://github.com/tailwindlabs/tailwindcss/pull/15663))
+- `outline-hidden` and `outline-none` behave the same in non-forced colors mode ([#15690](https://github.com/tailwindlabs/tailwindcss/pull/15690))
 
 ## [4.0.0-beta.9] - 2025-01-09
 

packages/tailwindcss/src/compat/default-theme.ts

@@ -1019,8 +1019,9 @@ export default {
     none: 'none',
     all: 'all',
     DEFAULT:
-      'color, background-color, border-color, text-decoration-color, fill, stroke, opacity, box-shadow, transform, filter, backdrop-filter',
-    colors: 'color, background-color, border-color, text-decoration-color, fill, stroke',
+      'color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, opacity, box-shadow, transform, filter, backdrop-filter',
+    colors:
+      'color, background-color, border-color, outline-color, text-decoration-color, fill, stroke',
     opacity: 'opacity',
     shadow: 'box-shadow',
     transform: 'transform',

packages/tailwindcss/src/utilities.test.ts

@@ -13873,7 +13873,7 @@ test('transition', async () => {
     }
 
     .transition {
-      transition-property: color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter;
+      transition-property: color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter;
       transition-timing-function: var(--tw-ease, var(--default-transition-timing-function));
       transition-duration: var(--tw-duration, var(--default-transition-duration));
     }
@@ -13891,7 +13891,7 @@ test('transition', async () => {
     }
 
     .transition-colors {
-      transition-property: color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to;
+      transition-property: color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to;
       transition-timing-function: var(--tw-ease, var(--default-transition-timing-function));
       transition-duration: var(--tw-duration, var(--default-transition-duration));
     }
@@ -13940,7 +13940,7 @@ test('transition', async () => {
     }
 
     .transition {
-      transition-property: color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter;
+      transition-property: color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter;
       transition-timing-function: var(--tw-ease, ease);
       transition-duration: var(--tw-duration, .1s);
     }
@@ -13952,7 +13952,7 @@ test('transition', async () => {
     }
 
     .transition-colors {
-      transition-property: color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to;
+      transition-property: color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to;
       transition-timing-function: var(--tw-ease, ease);
       transition-duration: var(--tw-duration, .1s);
     }"
@@ -14543,6 +14543,7 @@ test('outline', async () => {
       `,
       [
         'outline',
+        'outline-hidden',
 
         // outline-style
         'outline-none',
@@ -14594,6 +14595,17 @@ test('outline', async () => {
       --color-red-500: #ef4444;
     }
 
+    .outline-hidden {
+      outline-style: none;
+    }
+
+    @media (forced-colors: active) {
+      .outline-hidden {
+        outline-offset: 2px;
+        outline: 2px solid #0000;
+      }
+    }
+
     .outline {
       outline-style: var(--tw-outline-style);
       outline-width: 1px;

packages/tailwindcss/src/utilities.ts

@@ -3552,7 +3552,7 @@ export function createUtilities(theme: Theme) {
     staticUtility('transition-colors', [
       [
         'transition-property',
-        'color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to',
+        'color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to',
       ],
       ['transition-timing-function', defaultTimingFunction],
       ['transition-duration', defaultDuration],
@@ -3575,7 +3575,7 @@ export function createUtilities(theme: Theme) {
 
     functionalUtility('transition', {
       defaultValue:
-        'color, background-color, border-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter',
+        'color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter',
       themeKeys: ['--transition-property'],
       handle: (value) => [
         decl('transition-property', value),
@@ -3850,10 +3850,15 @@ export function createUtilities(theme: Theme) {
       return atRoot([property('--tw-outline-style', 'solid')])
     }
 
-    staticUtility('outline-hidden', [
-      ['outline', '2px solid transparent'],
-      ['outline-offset', '2px'],
-    ])
+    utilities.static('outline-hidden', () => {
+      return [
+        decl('outline-style', 'none'),
+        atRule('@media', '(forced-colors: active)', [
+          decl('outline', '2px solid transparent'),
+          decl('outline-offset', '2px'),
+        ]),
+      ]
+    })
 
     /**
      * @css `outline-style`