Apply suggestions from code review

Co-authored-by: Adam Wathan <[email protected]>

Author: philipp-spiess

CHANGELOG.md

@@ -7,9 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-### Added
+### Changed
 
-- No longer require escaping underscores for CSS variables used in `var()` ([#14776](https://github.com/tailwindlabs/tailwindcss/pull/14776))
+- Don't convert underscores in the first argument to `var()` to spaces ([#14776](https://github.com/tailwindlabs/tailwindcss/pull/14776))
 
 ### Fixed
 

packages/tailwindcss/src/candidate.test.ts

@@ -1080,7 +1080,7 @@ it('should not replace `_` inside of `url()`', () => {
     `)
 })
 
-it('should not replace `_` for the first value of `var()`', () => {
+it('should not replace `_` in the first argument to `var()`', () => {
   let utilities = new Utilities()
   utilities.functional('ml', () => [])
 

packages/tailwindcss/src/index.test.ts

@@ -116,7 +116,7 @@ describe('compiling CSS', () => {
     ).toMatchSnapshot()
   })
 
-  test('unescapes underscores to spaces inside arbitrary values expect for url() and first parameter of var()', async () => {
+  test('unescapes underscores to spaces inside arbitrary values except for `url()` and first argument of `var()`', async () => {
     expect(
       await compileCss(
         css`

packages/tailwindcss/src/utils/decode-arbitrary-value.ts

@@ -2,7 +2,7 @@ import * as ValueParser from '../value-parser'
 import { addWhitespaceAroundMathOperators } from './math-operators'
 
 export function decodeArbitraryValue(input: string): string {
-  // There's definitely no functions in the input, so bail early
+  // There are definitely no functions in the input, so bail early
   if (input.indexOf('(') === -1) {
     return convertUnderscoresToWhitespace(input)
   }