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gh-djankies-claude-configs-…/skills/migrating-from-v3/references/breaking-changes.md
2025-11-29 18:22:33 +08:00

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# Complete Breaking Changes List
## Configuration System
### JavaScript → CSS Configuration
**Breaking:** No more `tailwind.config.js` file.
**v3:**
```javascript
module.exports = {
theme: {
extend: {
colors: { brand: '#3b82f6' },
},
},
};
```
**v4:**
```css
@theme {
--color-brand: oklch(0.65 0.25 270);
}
```
**Impact:** All theme customization moves to CSS.
### Content Detection
**Breaking:** No manual content array needed.
**v3:**
```javascript
content: ['./src/**/*.{html,js}']
```
**v4:**
Automatic detection. Manual control via `@source` if needed.
**Impact:** Simplified setup, but less explicit control.
## Import Directives
### @tailwind → @import
**Breaking:** Different import syntax.
**v3:**
```css
@tailwind base;
@tailwind components;
@tailwind utilities;
```
**v4:**
```css
@import 'tailwindcss';
```
**Impact:** All templates need updating.
## Utility Class Changes
### Opacity Modifiers Removed
**Breaking:** Separate opacity utilities removed.
**v3:**
```html
<div class="bg-black bg-opacity-50"></div>
<div class="text-gray-900 text-opacity-75"></div>
<div class="border-blue-500 border-opacity-60"></div>
<div class="ring-blue-500 ring-opacity-30"></div>
```
**v4:**
```html
<div class="bg-black/50"></div>
<div class="text-gray-900/75"></div>
<div class="border-blue-500/60"></div>
<div class="ring-blue-500/30"></div>
```
**Impact:** Search and replace needed across entire codebase.
**Automated fix:**
```bash
find . -name "*.html" -o -name "*.jsx" -o -name "*.tsx" | xargs sed -i '' 's/bg-\([a-z-]*\) bg-opacity-\([0-9]*\)/bg-\1\/\2/g'
```
### Flex Utility Renames
**Breaking:** Utility names changed.
**v3:**
```html
<div class="flex-shrink-0"></div>
<div class="flex-shrink"></div>
<div class="flex-grow-0"></div>
<div class="flex-grow"></div>
```
**v4:**
```html
<div class="shrink-0"></div>
<div class="shrink"></div>
<div class="grow-0"></div>
<div class="grow"></div>
```
**Impact:** All flex utilities need renaming.
### Shadow Utility Rename
**Breaking:** Smallest shadow renamed.
**v3:**
```html
<div class="shadow-sm"></div>
```
**v4:**
```html
<div class="shadow-xs"></div>
```
**Impact:** Update all uses of `shadow-sm`.
### Ring Default Width
**Breaking:** Default ring width changed.
**v3:**
```html
<input class="ring" />
```
Ring width: 3px
**v4:**
```html
<input class="ring" />
```
Ring width: 1px
**Fix for v3 behavior:**
```html
<input class="ring-3" />
```
**Impact:** All bare `ring` utilities render thinner.
## Color System
### Default Border Color
**Breaking:** Border color changed from gray to currentColor.
**v3:**
```html
<div class="border"></div>
```
Border color: gray-200
**v4:**
```html
<div class="border"></div>
```
Border color: currentColor (inherits text color)
**Fix for v3 behavior:**
```html
<div class="border border-gray-200"></div>
```
**Impact:** Borders may appear different colors.
### Default Ring Color
**Breaking:** Ring color changed from blue to currentColor.
**v3:**
```html
<input class="ring" />
```
Ring color: blue-500
**v4:**
```html
<input class="ring" />
```
Ring color: currentColor
**Fix for v3 behavior:**
```html
<input class="ring ring-blue-500" />
```
**Impact:** Rings inherit text color.
### OkLCh Color Space
**Breaking:** Color values use OkLCh instead of RGB.
**v3:**
```javascript
colors: {
brand: '#3b82f6',
}
```
**v4:**
```css
@theme {
--color-brand: oklch(0.65 0.25 270);
}
```
**Impact:** Custom colors need conversion. Colors may look slightly different (more vivid on modern displays).
## PostCSS Changes
### Plugin Name
**Breaking:** Different PostCSS plugin.
**v3:**
```javascript
plugins: {
'tailwindcss': {},
'autoprefixer': {},
}
```
**v4:**
```javascript
plugins: {
'@tailwindcss/postcss': {},
}
```
**Impact:** PostCSS config needs updating. Remove `autoprefixer` and `postcss-import` (no longer needed).
## Preflight Changes
### Placeholder Color
**Breaking:** Placeholder text color changed.
**v3:**
```css
::placeholder {
color: theme('colors.gray.400');
}
```
**v4:**
```css
::placeholder {
color: currentColor;
opacity: 0.5;
}
```
**Impact:** Placeholders inherit text color at 50% opacity.
**Fix for v3 behavior:**
```css
@layer base {
::placeholder {
color: theme('colors.gray.400');
opacity: 1;
}
}
```
### Button Cursor
**Breaking:** Button cursor changed.
**v3:**
```css
button {
cursor: pointer;
}
```
**v4:**
```css
button {
cursor: default;
}
```
**Impact:** Buttons no longer show pointer cursor by default.
**Fix for v3 behavior:**
```css
@layer base {
button {
cursor: pointer;
}
}
```
Or add explicit classes:
```html
<button class="cursor-pointer">Click me</button>
```
## Arbitrary Values
### Space Handling
**Breaking:** Spaces in arbitrary values use underscores.
**v3:**
```html
<div class="grid-cols-[1fr,500px,2fr]"></div>
```
**v4:**
```html
<div class="grid-cols-[1fr_500px_2fr]"></div>
```
**Impact:** All arbitrary values with commas need updating.
## Browser Support
### Minimum Versions
**Breaking:** Dropped support for older browsers.
**v3:**
- IE 11+
- Safari 10+
- Chrome 60+
**v4:**
- Safari 16.4+
- Chrome 111+
- Firefox 128+
**Impact:** Projects requiring older browser support cannot upgrade.
## CSS Preprocessors
### No Sass/Less/Stylus Support
**Breaking:** Incompatible with CSS preprocessors.
**v3:**
Can use with Sass, Less, Stylus
**v4:**
Cannot use CSS preprocessors (Tailwind functions as preprocessing layer)
**Impact:** Remove CSS preprocessors from build pipeline.
## Plugin System
### Plugin API Changes
**Breaking:** Plugin API completely rewritten.
**v3 plugin:**
```javascript
const plugin = require('tailwindcss/plugin');
module.exports = plugin(function ({ addUtilities, theme }) {
addUtilities({
'.content-auto': {
'content-visibility': 'auto',
},
});
});
```
**v4 equivalent:**
```css
@utility content-auto {
content-visibility: auto;
}
```
**Impact:** All custom plugins need manual rewrite.
## @apply Restrictions
### Limited @apply Support
**Breaking:** @apply only works for small subset of utilities.
**v3:**
```css
.btn {
@apply px-4 py-2 bg-blue-600 text-white rounded-md hover:bg-blue-700;
}
```
**v4:**
@apply has limited support. Use @utility instead:
```css
@utility btn {
padding: var(--spacing-2) var(--spacing-4);
background: var(--color-blue-600);
color: var(--color-white);
border-radius: var(--radius-md);
}
```
**Impact:** Many @apply patterns need refactoring.
## Mobile Hover Behavior
### Hover on Touch Devices
**Breaking:** Hover styles don't apply on touch devices.
**v3:**
Hover styles triggered on tap
**v4:**
Hover styles only on devices supporting hover
**Impact:** Touch devices won't show hover states (improves UX).
## Container Plugin
### Built-in Container Queries
**Breaking:** Container queries plugin no longer needed.
**v3:**
```javascript
plugins: [require('@tailwindcss/container-queries')]
```
**v4:**
Built-in. No plugin needed.
**Impact:** Remove plugin dependency. Syntax remains same.
## Summary Table
| Change | v3 | v4 | Impact |
|--------|----|----|--------|
| Config | tailwind.config.js | @theme | High |
| Import | @tailwind | @import | High |
| Opacity | bg-opacity-50 | bg-{color}/50 | High |
| Flex | flex-shrink | shrink | Medium |
| Shadow | shadow-sm | shadow-xs | Low |
| Ring width | 3px | 1px | Medium |
| Border color | gray-200 | currentColor | Medium |
| Color space | RGB | OkLCh | Medium |
| PostCSS | tailwindcss | @tailwindcss/postcss | High |
| Placeholder | gray-400 | currentColor/50 | Low |
| Button cursor | pointer | default | Low |
| Browsers | IE 11+ | Safari 16.4+ | High |
| Preprocessors | Supported | Not supported | High |
| Plugins | JS API | CSS @utility | High |