From 354b706e88ac4d560d3804997ae8a1407edbd9dc Mon Sep 17 00:00:00 2001
From: ish1416 <ish1442006@gmail.com>
Date: Sat, 8 Nov 2025 13:48:50 +0530
Subject: [PATCH 01/11] fix: include filename and line numbers in CSS parse
 errors

- Add getLineAndColumn helper to calculate position from buffer index
- Add formatError helper to format errors with source location
- Update all CSS parser error messages to include filename:line:column
- Add comprehensive test coverage for error reporting
- Maintain backward compatibility when no filename provided

Fixes #19236
---
 integrations/cli/index.test.ts              | 28 +++++++++++
 packages/tailwindcss/src/css-parser.test.ts | 56 +++++++++++++++++++++
 packages/tailwindcss/src/css-parser.ts      | 49 +++++++++++++-----
 3 files changed, 121 insertions(+), 12 deletions(-)

diff --git a/integrations/cli/index.test.ts b/integrations/cli/index.test.ts
index 9b666f4ec313..b17bc8a8f45d 100644
--- a/integrations/cli/index.test.ts
+++ b/integrations/cli/index.test.ts
@@ -2104,3 +2104,31 @@ test(
 function withBOM(text: string): string {
   return '\uFEFF' + text
 }
+
+test(
+  'CSS parse errors should include filename and line number',
+  {
+    fs: {
+      'package.json': json`
+        {
+          "dependencies": {
+            "tailwindcss": "workspace:^",
+            "@tailwindcss/cli": "workspace:^"
+          }
+        }
+      `,
+      'broken.css': css`
+        /* Test file to reproduce the CSS parsing error */
+        .test {
+          color: red;
+          /* margin-bottom: calc(var(--spacing) * 5); */ */
+        }
+      `,
+    },
+  },
+  async ({ exec, expect }) => {
+    await expect(exec('pnpm tailwindcss --input broken.css --output dist/out.css')).rejects.toThrow(
+      /Invalid declaration.*at.*broken\.css:5:49/,
+    )
+  },
+)
diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index 25657d9db770..10a38d9e9e95 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -1215,6 +1215,54 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
         `[Error: Invalid declaration: \`bar\`]`,
       )
     })
+
+    it('should include filename and line number in error messages when from option is provided', () => {
+      expect(() => {
+        CSS.parse('/* margin-bottom: calc(var(--spacing) * 5); */ */', { from: 'test.css' })
+      }).toThrowErrorMatchingInlineSnapshot(
+        `[Error: Invalid declaration: \`*/\` at test.css:1:49]`,
+      )
+    })
+
+    it('should include filename and line number for multi-line CSS errors', () => {
+      const multiLineCss = `/* Test file */
+.test {
+  color: red;
+  /* margin-bottom: calc(var(--spacing) * 5); */ */
+}`
+      expect(() => {
+        CSS.parse(multiLineCss, { from: 'styles.css' })
+      }).toThrowErrorMatchingInlineSnapshot(
+        `[Error: Invalid declaration: \`*/\` at styles.css:4:49]`,
+      )
+    })
+
+    it('should include filename and line number for missing opening brace errors', () => {
+      const cssWithMissingBrace = `.foo {
+  color: red;
+}
+
+.bar
+  color: blue;
+}`
+      expect(() => {
+        CSS.parse(cssWithMissingBrace, { from: 'broken.css' })
+      }).toThrowErrorMatchingInlineSnapshot(
+        `[Error: Missing opening { at broken.css:7:1]`,
+      )
+    })
+
+    it('should include filename and line number for unterminated string errors', () => {
+      const cssWithUnterminatedString = `.foo {
+  content: "Hello world!
+  font-weight: bold;
+}`
+      expect(() => {
+        CSS.parse(cssWithUnterminatedString, { from: 'string-error.css' })
+      }).toThrowErrorMatchingInlineSnapshot(
+        `[Error: Unterminated string: "Hello world! at string-error.css:2:12]`,
+      )
+    })
   })
 
   it('ignores BOM at the beginning of a file', () => {
@@ -1227,4 +1275,12 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       },
     ])
   })
+
+  it('should not include filename when from option is not provided', () => {
+    expect(() => {
+      CSS.parse('/* margin-bottom: calc(var(--spacing) * 5); */ */')
+    }).toThrowErrorMatchingInlineSnapshot(
+      `[Error: Invalid declaration: \`*/\`]`,
+    )
+  })
 })
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 1653c3789b28..1105d149b82e 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -36,6 +36,31 @@ export interface ParseOptions {
   from?: string
 }
 
+function getLineAndColumn(input: string, position: number): { line: number; column: number } {
+  let line = 1
+  let column = 1
+  
+  for (let i = 0; i < position && i < input.length; i++) {
+    if (input.charCodeAt(i) === LINE_BREAK) {
+      line++
+      column = 1
+    } else {
+      column++
+    }
+  }
+  
+  return { line, column }
+}
+
+function formatError(message: string, source: Source | null, position: number): string {
+  if (!source) {
+    return message
+  }
+  
+  const { line, column } = getLineAndColumn(source.code, position)
+  return `${message} at ${source.file}:${line}:${column}`
+}
+
 export function parse(input: string, opts?: ParseOptions) {
   let source: Source | null = opts?.from ? { file: opts.from, code: input } : null
 
@@ -138,7 +163,7 @@ export function parse(input: string, opts?: ParseOptions) {
 
     // Start of a string.
     else if (currentChar === SINGLE_QUOTE || currentChar === DOUBLE_QUOTE) {
-      let end = parseString(input, i, currentChar)
+      let end = parseString(input, i, currentChar, source)
 
       // Adjust `buffer` to include the string.
       buffer += input.slice(i, end + 1)
@@ -192,7 +217,7 @@ export function parse(input: string, opts?: ParseOptions) {
 
         // Start of a string.
         else if (peekChar === SINGLE_QUOTE || peekChar === DOUBLE_QUOTE) {
-          j = parseString(input, j, peekChar)
+          j = parseString(input, j, peekChar, source)
         }
 
         // Start of a comment.
@@ -269,7 +294,7 @@ export function parse(input: string, opts?: ParseOptions) {
       }
 
       let declaration = parseDeclaration(buffer, colonIdx)
-      if (!declaration) throw new Error(`Invalid custom property, expected a value`)
+      if (!declaration) throw new Error(formatError(`Invalid custom property, expected a value`, source, start))
 
       if (source) {
         declaration.src = [source, start, i]
@@ -334,7 +359,7 @@ export function parse(input: string, opts?: ParseOptions) {
       let declaration = parseDeclaration(buffer)
       if (!declaration) {
         if (buffer.length === 0) continue
-        throw new Error(`Invalid declaration: \`${buffer.trim()}\``)
+        throw new Error(formatError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart))
       }
 
       if (source) {
@@ -391,7 +416,7 @@ export function parse(input: string, opts?: ParseOptions) {
       closingBracketStack[closingBracketStack.length - 1] !== ')'
     ) {
       if (closingBracketStack === '') {
-        throw new Error('Missing opening {')
+        throw new Error(formatError('Missing opening {', source, i))
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -453,7 +478,7 @@ export function parse(input: string, opts?: ParseOptions) {
           // Attach the declaration to the parent.
           if (parent) {
             let node = parseDeclaration(buffer, colonIdx)
-            if (!node) throw new Error(`Invalid declaration: \`${buffer.trim()}\``)
+            if (!node) throw new Error(formatError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart))
 
             if (source) {
               node.src = [source, bufferStart, i]
@@ -492,7 +517,7 @@ export function parse(input: string, opts?: ParseOptions) {
     // `)`
     else if (currentChar === CLOSE_PAREN) {
       if (closingBracketStack[closingBracketStack.length - 1] !== ')') {
-        throw new Error('Missing opening (')
+        throw new Error(formatError('Missing opening (', source, i))
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -534,10 +559,10 @@ export function parse(input: string, opts?: ParseOptions) {
   // have a leftover `parent`, then it means that we have an unterminated block.
   if (closingBracketStack.length > 0 && parent) {
     if (parent.kind === 'rule') {
-      throw new Error(`Missing closing } at ${parent.selector}`)
+      throw new Error(formatError(`Missing closing } at ${parent.selector}`, source, input.length))
     }
     if (parent.kind === 'at-rule') {
-      throw new Error(`Missing closing } at ${parent.name} ${parent.params}`)
+      throw new Error(formatError(`Missing closing } at ${parent.name} ${parent.params}`, source, input.length))
     }
   }
 
@@ -594,7 +619,7 @@ function parseDeclaration(
   )
 }
 
-function parseString(input: string, startIdx: number, quoteChar: number): number {
+function parseString(input: string, startIdx: number, quoteChar: number, source: Source | null = null): number {
   let peekChar: number
 
   // We need to ensure that the closing quote is the same as the opening
@@ -637,7 +662,7 @@ function parseString(input: string, startIdx: number, quoteChar: number): number
         (input.charCodeAt(i + 1) === CARRIAGE_RETURN && input.charCodeAt(i + 2) === LINE_BREAK))
     ) {
       throw new Error(
-        `Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`,
+        formatError(`Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`, source, startIdx)
       )
     }
 
@@ -656,7 +681,7 @@ function parseString(input: string, startIdx: number, quoteChar: number): number
       (peekChar === CARRIAGE_RETURN && input.charCodeAt(i + 1) === LINE_BREAK)
     ) {
       throw new Error(
-        `Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`,
+        formatError(`Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`, source, startIdx)
       )
     }
   }

From 667f1c752116bd23b460dcee3e74866b847e7ba3 Mon Sep 17 00:00:00 2001
From: ish1416 <ish1442006@gmail.com>
Date: Mon, 10 Nov 2025 12:47:06 +0530
Subject: [PATCH 02/11] fix: correct test cases for CssSyntaxError

- Use simpler CSS that actually triggers parse errors
- Fix regex patterns to match actual error output
- Remove inline snapshots from describe.each blocks
- Update CLI test to match actual error line numbers

All tests should now pass with the CssSyntaxError implementation.
---
 integrations/cli/index.test.ts              |  7 ++-
 packages/tailwindcss/src/css-parser.test.ts | 26 ++++-------
 packages/tailwindcss/src/css-parser.ts      | 50 ++++++++-------------
 3 files changed, 32 insertions(+), 51 deletions(-)

diff --git a/integrations/cli/index.test.ts b/integrations/cli/index.test.ts
index b17bc8a8f45d..adce6e71bfe6 100644
--- a/integrations/cli/index.test.ts
+++ b/integrations/cli/index.test.ts
@@ -1,9 +1,12 @@
 import dedent from 'dedent'
 import os from 'node:os'
 import path from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { describe } from 'vitest'
 import { candidate, css, html, js, json, test, ts, yaml } from '../utils'
 
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+
 const STANDALONE_BINARY = (() => {
   switch (os.platform()) {
     case 'win32':
@@ -2121,14 +2124,14 @@ test(
         /* Test file to reproduce the CSS parsing error */
         .test {
           color: red;
-          /* margin-bottom: calc(var(--spacing) * 5); */ */
+          */
         }
       `,
     },
   },
   async ({ exec, expect }) => {
     await expect(exec('pnpm tailwindcss --input broken.css --output dist/out.css')).rejects.toThrow(
-      /Invalid declaration.*at.*broken\.css:5:49/,
+      /Invalid declaration.*at.*broken\.css:4:/,
     )
   },
 )
diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index 10a38d9e9e95..f65d51e0f572 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -1218,23 +1218,19 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 
     it('should include filename and line number in error messages when from option is provided', () => {
       expect(() => {
-        CSS.parse('/* margin-bottom: calc(var(--spacing) * 5); */ */', { from: 'test.css' })
-      }).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Invalid declaration: \`*/\` at test.css:1:49]`,
-      )
+        CSS.parse('.test { */ }', { from: 'test.css' })
+      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at test\.css:1:9/)
     })
 
     it('should include filename and line number for multi-line CSS errors', () => {
       const multiLineCss = `/* Test file */
 .test {
   color: red;
-  /* margin-bottom: calc(var(--spacing) * 5); */ */
+  */
 }`
       expect(() => {
         CSS.parse(multiLineCss, { from: 'styles.css' })
-      }).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Invalid declaration: \`*/\` at styles.css:4:49]`,
-      )
+      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at styles\.css:4:3/)
     })
 
     it('should include filename and line number for missing opening brace errors', () => {
@@ -1247,9 +1243,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 }`
       expect(() => {
         CSS.parse(cssWithMissingBrace, { from: 'broken.css' })
-      }).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Missing opening { at broken.css:7:1]`,
-      )
+      }).toThrow(/CssSyntaxError: Missing opening \{ at broken\.css:7:1/)
     })
 
     it('should include filename and line number for unterminated string errors', () => {
@@ -1259,9 +1253,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 }`
       expect(() => {
         CSS.parse(cssWithUnterminatedString, { from: 'string-error.css' })
-      }).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Unterminated string: "Hello world! at string-error.css:2:12]`,
-      )
+      }).toThrow(/CssSyntaxError: Unterminated string: "Hello world!" at string-error\.css:2:12/)
     })
   })
 
@@ -1278,9 +1270,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 
   it('should not include filename when from option is not provided', () => {
     expect(() => {
-      CSS.parse('/* margin-bottom: calc(var(--spacing) * 5); */ */')
-    }).toThrowErrorMatchingInlineSnapshot(
-      `[Error: Invalid declaration: \`*/\`]`,
-    )
+      CSS.parse('.test { */ }')
+    }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/`$/)
   })
 })
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 1105d149b82e..000a9e11e0df 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -9,6 +9,7 @@ import {
   type Declaration,
   type Rule,
 } from './ast'
+import { createLineTable } from './source-maps/line-table'
 import type { Source } from './source-maps/source'
 
 const BACKSLASH = 0x5c
@@ -36,29 +37,16 @@ export interface ParseOptions {
   from?: string
 }
 
-function getLineAndColumn(input: string, position: number): { line: number; column: number } {
-  let line = 1
-  let column = 1
-  
-  for (let i = 0; i < position && i < input.length; i++) {
-    if (input.charCodeAt(i) === LINE_BREAK) {
-      line++
-      column = 1
+export class CssSyntaxError extends Error {
+  constructor(message: string, source: Source | null, position: number) {
+    if (!source) {
+      super(message)
     } else {
-      column++
+      const { line, column } = createLineTable(source.code).find(position)
+      super(`${message} at ${source.file}:${line}:${column}`)
     }
+    this.name = 'CssSyntaxError'
   }
-  
-  return { line, column }
-}
-
-function formatError(message: string, source: Source | null, position: number): string {
-  if (!source) {
-    return message
-  }
-  
-  const { line, column } = getLineAndColumn(source.code, position)
-  return `${message} at ${source.file}:${line}:${column}`
 }
 
 export function parse(input: string, opts?: ParseOptions) {
@@ -294,7 +282,7 @@ export function parse(input: string, opts?: ParseOptions) {
       }
 
       let declaration = parseDeclaration(buffer, colonIdx)
-      if (!declaration) throw new Error(formatError(`Invalid custom property, expected a value`, source, start))
+      if (!declaration) throw new CssSyntaxError(`Invalid custom property, expected a value`, source, start)
 
       if (source) {
         declaration.src = [source, start, i]
@@ -359,7 +347,7 @@ export function parse(input: string, opts?: ParseOptions) {
       let declaration = parseDeclaration(buffer)
       if (!declaration) {
         if (buffer.length === 0) continue
-        throw new Error(formatError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart))
+        throw new CssSyntaxError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart)
       }
 
       if (source) {
@@ -416,7 +404,7 @@ export function parse(input: string, opts?: ParseOptions) {
       closingBracketStack[closingBracketStack.length - 1] !== ')'
     ) {
       if (closingBracketStack === '') {
-        throw new Error(formatError('Missing opening {', source, i))
+        throw new CssSyntaxError('Missing opening {', source, i)
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -478,7 +466,7 @@ export function parse(input: string, opts?: ParseOptions) {
           // Attach the declaration to the parent.
           if (parent) {
             let node = parseDeclaration(buffer, colonIdx)
-            if (!node) throw new Error(formatError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart))
+            if (!node) throw new CssSyntaxError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart)
 
             if (source) {
               node.src = [source, bufferStart, i]
@@ -517,7 +505,7 @@ export function parse(input: string, opts?: ParseOptions) {
     // `)`
     else if (currentChar === CLOSE_PAREN) {
       if (closingBracketStack[closingBracketStack.length - 1] !== ')') {
-        throw new Error(formatError('Missing opening (', source, i))
+        throw new CssSyntaxError('Missing opening (', source, i)
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -559,10 +547,10 @@ export function parse(input: string, opts?: ParseOptions) {
   // have a leftover `parent`, then it means that we have an unterminated block.
   if (closingBracketStack.length > 0 && parent) {
     if (parent.kind === 'rule') {
-      throw new Error(formatError(`Missing closing } at ${parent.selector}`, source, input.length))
+      throw new CssSyntaxError(`Missing closing } at ${parent.selector}`, source, input.length)
     }
     if (parent.kind === 'at-rule') {
-      throw new Error(formatError(`Missing closing } at ${parent.name} ${parent.params}`, source, input.length))
+      throw new CssSyntaxError(`Missing closing } at ${parent.name} ${parent.params}`, source, input.length)
     }
   }
 
@@ -661,8 +649,8 @@ function parseString(input: string, startIdx: number, quoteChar: number, source:
       (input.charCodeAt(i + 1) === LINE_BREAK ||
         (input.charCodeAt(i + 1) === CARRIAGE_RETURN && input.charCodeAt(i + 2) === LINE_BREAK))
     ) {
-      throw new Error(
-        formatError(`Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`, source, startIdx)
+      throw new CssSyntaxError(
+        `Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`, source, startIdx
       )
     }
 
@@ -680,8 +668,8 @@ function parseString(input: string, startIdx: number, quoteChar: number, source:
       peekChar === LINE_BREAK ||
       (peekChar === CARRIAGE_RETURN && input.charCodeAt(i + 1) === LINE_BREAK)
     ) {
-      throw new Error(
-        formatError(`Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`, source, startIdx)
+      throw new CssSyntaxError(
+        `Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`, source, startIdx
       )
     }
   }

From d9d5ea31f3226ceab05462c3c19db6e2c4cfdaab Mon Sep 17 00:00:00 2001
From: ish1416 <ish1442006@gmail.com>
Date: Mon, 10 Nov 2025 13:05:38 +0530
Subject: [PATCH 03/11] fix: correct column number to be 1-based

createLineTable().find() returns 0-based columns per source map spec,
but users expect 1-based column numbers. Add 1 to column before
formatting error message so both line and column are 1-based and accurate.

Addresses reviewer feedback about off-by-one column numbers.
---
 packages/tailwindcss/src/css-parser.test.ts | 8 ++++----
 packages/tailwindcss/src/css-parser.ts      | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index f65d51e0f572..4a796d8cf360 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -1219,7 +1219,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
     it('should include filename and line number in error messages when from option is provided', () => {
       expect(() => {
         CSS.parse('.test { */ }', { from: 'test.css' })
-      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at test\.css:1:9/)
+      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at test\.css:1:10/)
     })
 
     it('should include filename and line number for multi-line CSS errors', () => {
@@ -1230,7 +1230,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 }`
       expect(() => {
         CSS.parse(multiLineCss, { from: 'styles.css' })
-      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at styles\.css:4:3/)
+      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at styles\.css:4:4/)
     })
 
     it('should include filename and line number for missing opening brace errors', () => {
@@ -1243,7 +1243,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 }`
       expect(() => {
         CSS.parse(cssWithMissingBrace, { from: 'broken.css' })
-      }).toThrow(/CssSyntaxError: Missing opening \{ at broken\.css:7:1/)
+      }).toThrow(/CssSyntaxError: Missing opening \{ at broken\.css:7:2/)
     })
 
     it('should include filename and line number for unterminated string errors', () => {
@@ -1253,7 +1253,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 }`
       expect(() => {
         CSS.parse(cssWithUnterminatedString, { from: 'string-error.css' })
-      }).toThrow(/CssSyntaxError: Unterminated string: "Hello world!" at string-error\.css:2:12/)
+      }).toThrow(/CssSyntaxError: Unterminated string: "Hello world!" at string-error\.css:2:13/)
     })
   })
 
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 000a9e11e0df..6561816faaef 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -43,7 +43,7 @@ export class CssSyntaxError extends Error {
       super(message)
     } else {
       const { line, column } = createLineTable(source.code).find(position)
-      super(`${message} at ${source.file}:${line}:${column}`)
+      super(`${message} at ${source.file}:${line}:${column + 1}`)
     }
     this.name = 'CssSyntaxError'
   }

From 53509a8231b7a03d691f4046ecb346111b89baf3 Mon Sep 17 00:00:00 2001
From: ish1416 <ish1442006@gmail.com>
Date: Mon, 10 Nov 2025 13:19:30 +0530
Subject: [PATCH 04/11] docs: add JSDoc to CssSyntaxError class

Add minimal JSDoc documentation to satisfy docstring coverage requirement
for the exported CssSyntaxError class.
---
 packages/tailwindcss/src/css-parser.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 6561816faaef..1e5d9f4579b2 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -37,6 +37,9 @@ export interface ParseOptions {
   from?: string
 }
 
+/**
+ * CSS syntax error with source location information.
+ */
 export class CssSyntaxError extends Error {
   constructor(message: string, source: Source | null, position: number) {
     if (!source) {

From 6f94fc231ed910f8955dafdb5b55c0c53aade823 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 09:18:55 -0500
Subject: [PATCH 05/11] Tweak code a bit

---
 packages/tailwindcss/src/css-parser.test.ts | 141 ++++++++++++--------
 packages/tailwindcss/src/css-parser.ts      |  70 +++++++---
 2 files changed, 141 insertions(+), 70 deletions(-)

diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index 4a796d8cf360..78326661678e 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -8,6 +8,12 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
     return CSS.parse(string.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'))
   }
 
+  function parseWithLoc(string: string) {
+    return CSS.parse(string.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'), {
+      from: 'input.css',
+    })
+  }
+
   describe('comments', () => {
     it('should parse a comment and ignore it', () => {
       expect(
@@ -1145,7 +1151,20 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
             color: blue;
           }
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[Error: Missing opening {]`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: Missing opening {]`)
+
+      expect(() =>
+        parseWithLoc(`
+          .foo {
+            color: red;
+          }
+
+          .bar
+            /* ^ Missing opening { */
+            color: blue;
+          }
+        `),
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: input.css: 9:10: Missing opening {]`)
     })
 
     it('should error when curly brackets are unbalanced (closing)', () => {
@@ -1160,7 +1179,22 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
 
        /* ^ Missing closing } */
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[Error: Missing closing } at .bar]`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: Missing closing } at .bar]`)
+
+      expect(() =>
+        parseWithLoc(`
+          .foo {
+            color: red;
+          }
+
+          .bar {
+            color: blue;
+
+       /* ^ Missing closing } */
+        `),
+      ).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 7:12: Missing closing } at .bar]`,
+      )
     })
 
     it('should error when an unterminated string is used', () => {
@@ -1172,7 +1206,19 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
             font-weight: bold;
           }
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[Error: Unterminated string: "Hello world!"]`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: Unterminated string: "Hello world!"]`)
+
+      expect(() =>
+        parseWithLoc(css`
+          .foo {
+            content: "Hello world!
+            /*                    ^ missing " */
+            font-weight: bold;
+          }
+        `),
+      ).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 3:21: Unterminated string: "Hello world!"]`,
+      )
     })
 
     it('should error when an unterminated string is used with a `;`', () => {
@@ -1184,18 +1230,38 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
             font-weight: bold;
           }
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[Error: Unterminated string: "Hello world!;"]`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: Unterminated string: "Hello world!;"]`)
+
+      expect(() =>
+        parseWithLoc(css`
+          .foo {
+            content: "Hello world!;
+            /*                    ^ missing " */
+            font-weight: bold;
+          }
+        `),
+      ).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 3:21: Unterminated string: "Hello world!;"]`,
+      )
     })
 
     it('should error when incomplete custom properties are used', () => {
       expect(() => parse('--foo')).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Invalid custom property, expected a value]`,
+        `[CssSyntaxError: Invalid custom property, expected a value]`,
+      )
+
+      expect(() => parseWithLoc('--foo')).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 1:0: Invalid custom property, expected a value]`,
       )
     })
 
     it('should error when incomplete custom properties are used inside rules', () => {
       expect(() => parse('.foo { --bar }')).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Invalid custom property, expected a value]`,
+        `[CssSyntaxError: Invalid custom property, expected a value]`,
+      )
+
+      expect(() => parseWithLoc('.foo { --bar }')).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 1:7: Invalid custom property, expected a value]`,
       )
     })
 
@@ -1207,53 +1273,28 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
             /*                  ^ missing ' * /;
           }
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[Error: Unterminated string: 'Hello world!']`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: Unterminated string: 'Hello world!']`)
+
+      expect(() =>
+        parseWithLoc(css`
+          .foo {
+            --bar: 'Hello world!
+            /*                  ^ missing ' * /;
+          }
+        `),
+      ).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 3:19: Unterminated string: 'Hello world!']`,
+      )
     })
 
     it('should error when a declaration is incomplete', () => {
       expect(() => parse('.foo { bar }')).toThrowErrorMatchingInlineSnapshot(
-        `[Error: Invalid declaration: \`bar\`]`,
+        `[CssSyntaxError: Invalid declaration: \`bar\`]`,
       )
-    })
-
-    it('should include filename and line number in error messages when from option is provided', () => {
-      expect(() => {
-        CSS.parse('.test { */ }', { from: 'test.css' })
-      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at test\.css:1:10/)
-    })
-
-    it('should include filename and line number for multi-line CSS errors', () => {
-      const multiLineCss = `/* Test file */
-.test {
-  color: red;
-  */
-}`
-      expect(() => {
-        CSS.parse(multiLineCss, { from: 'styles.css' })
-      }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/` at styles\.css:4:4/)
-    })
-
-    it('should include filename and line number for missing opening brace errors', () => {
-      const cssWithMissingBrace = `.foo {
-  color: red;
-}
-
-.bar
-  color: blue;
-}`
-      expect(() => {
-        CSS.parse(cssWithMissingBrace, { from: 'broken.css' })
-      }).toThrow(/CssSyntaxError: Missing opening \{ at broken\.css:7:2/)
-    })
 
-    it('should include filename and line number for unterminated string errors', () => {
-      const cssWithUnterminatedString = `.foo {
-  content: "Hello world!
-  font-weight: bold;
-}`
-      expect(() => {
-        CSS.parse(cssWithUnterminatedString, { from: 'string-error.css' })
-      }).toThrow(/CssSyntaxError: Unterminated string: "Hello world!" at string-error\.css:2:13/)
+      expect(() => parseWithLoc('.foo { bar }')).toThrowErrorMatchingInlineSnapshot(
+        `[CssSyntaxError: input.css: 1:7: Invalid declaration: \`bar\`]`,
+      )
     })
   })
 
@@ -1267,10 +1308,4 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       },
     ])
   })
-
-  it('should not include filename when from option is not provided', () => {
-    expect(() => {
-      CSS.parse('.test { */ }')
-    }).toThrow(/CssSyntaxError: Invalid declaration: `\*\/`$/)
-  })
 })
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 1e5d9f4579b2..4d6cd1a8a469 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -10,7 +10,7 @@ import {
   type Rule,
 } from './ast'
 import { createLineTable } from './source-maps/line-table'
-import type { Source } from './source-maps/source'
+import type { Source, SourceLocation } from './source-maps/source'
 
 const BACKSLASH = 0x5c
 const SLASH = 0x2f
@@ -41,14 +41,23 @@ export interface ParseOptions {
  * CSS syntax error with source location information.
  */
 export class CssSyntaxError extends Error {
-  constructor(message: string, source: Source | null, position: number) {
-    if (!source) {
-      super(message)
-    } else {
-      const { line, column } = createLineTable(source.code).find(position)
-      super(`${message} at ${source.file}:${line}:${column + 1}`)
+  loc: SourceLocation | null
+
+  constructor(message: string, loc: SourceLocation | null) {
+    if (loc) {
+      let source = loc[0]
+      let start = createLineTable(source.code).find(loc[1])
+      message = `${source.file}: ${start.line}:${start.column}: ${message}`
     }
+
+    super(message)
+
     this.name = 'CssSyntaxError'
+    this.loc = loc
+
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(this, CssSyntaxError)
+    }
   }
 }
 
@@ -285,7 +294,12 @@ export function parse(input: string, opts?: ParseOptions) {
       }
 
       let declaration = parseDeclaration(buffer, colonIdx)
-      if (!declaration) throw new CssSyntaxError(`Invalid custom property, expected a value`, source, start)
+      if (!declaration) {
+        throw new CssSyntaxError(
+          `Invalid custom property, expected a value`,
+          source ? [source, start, i] : null,
+        )
+      }
 
       if (source) {
         declaration.src = [source, start, i]
@@ -350,7 +364,10 @@ export function parse(input: string, opts?: ParseOptions) {
       let declaration = parseDeclaration(buffer)
       if (!declaration) {
         if (buffer.length === 0) continue
-        throw new CssSyntaxError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart)
+        throw new CssSyntaxError(
+          `Invalid declaration: \`${buffer.trim()}\``,
+          source ? [source, bufferStart, i] : null,
+        )
       }
 
       if (source) {
@@ -407,7 +424,7 @@ export function parse(input: string, opts?: ParseOptions) {
       closingBracketStack[closingBracketStack.length - 1] !== ')'
     ) {
       if (closingBracketStack === '') {
-        throw new CssSyntaxError('Missing opening {', source, i)
+        throw new CssSyntaxError('Missing opening {', source ? [source, i, i] : null)
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -469,7 +486,12 @@ export function parse(input: string, opts?: ParseOptions) {
           // Attach the declaration to the parent.
           if (parent) {
             let node = parseDeclaration(buffer, colonIdx)
-            if (!node) throw new CssSyntaxError(`Invalid declaration: \`${buffer.trim()}\``, source, bufferStart)
+            if (!node) {
+              throw new CssSyntaxError(
+                `Invalid declaration: \`${buffer.trim()}\``,
+                source ? [source, bufferStart, i] : null,
+              )
+            }
 
             if (source) {
               node.src = [source, bufferStart, i]
@@ -508,7 +530,7 @@ export function parse(input: string, opts?: ParseOptions) {
     // `)`
     else if (currentChar === CLOSE_PAREN) {
       if (closingBracketStack[closingBracketStack.length - 1] !== ')') {
-        throw new CssSyntaxError('Missing opening (', source, i)
+        throw new CssSyntaxError('Missing opening (', source ? [source, i, i] : null)
       }
 
       closingBracketStack = closingBracketStack.slice(0, -1)
@@ -550,10 +572,17 @@ export function parse(input: string, opts?: ParseOptions) {
   // have a leftover `parent`, then it means that we have an unterminated block.
   if (closingBracketStack.length > 0 && parent) {
     if (parent.kind === 'rule') {
-      throw new CssSyntaxError(`Missing closing } at ${parent.selector}`, source, input.length)
+      throw new CssSyntaxError(
+        `Missing closing } at ${parent.selector}`,
+        source ? [source, bufferStart, bufferStart] : null,
+      )
     }
+
     if (parent.kind === 'at-rule') {
-      throw new CssSyntaxError(`Missing closing } at ${parent.name} ${parent.params}`, source, input.length)
+      throw new CssSyntaxError(
+        `Missing closing } at ${parent.name} ${parent.params}`,
+        source ? [source, bufferStart, bufferStart] : null,
+      )
     }
   }
 
@@ -610,7 +639,12 @@ function parseDeclaration(
   )
 }
 
-function parseString(input: string, startIdx: number, quoteChar: number, source: Source | null = null): number {
+function parseString(
+  input: string,
+  startIdx: number,
+  quoteChar: number,
+  source: Source | null = null,
+): number {
   let peekChar: number
 
   // We need to ensure that the closing quote is the same as the opening
@@ -653,7 +687,8 @@ function parseString(input: string, startIdx: number, quoteChar: number, source:
         (input.charCodeAt(i + 1) === CARRIAGE_RETURN && input.charCodeAt(i + 2) === LINE_BREAK))
     ) {
       throw new CssSyntaxError(
-        `Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`, source, startIdx
+        `Unterminated string: ${input.slice(startIdx, i + 1) + String.fromCharCode(quoteChar)}`,
+        source ? [source, startIdx, i + 1] : null,
       )
     }
 
@@ -672,7 +707,8 @@ function parseString(input: string, startIdx: number, quoteChar: number, source:
       (peekChar === CARRIAGE_RETURN && input.charCodeAt(i + 1) === LINE_BREAK)
     ) {
       throw new CssSyntaxError(
-        `Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`, source, startIdx
+        `Unterminated string: ${input.slice(startIdx, i) + String.fromCharCode(quoteChar)}`,
+        source ? [source, startIdx, i + 1] : null,
       )
     }
   }

From e18642a61626d850027acc51008fd636b75df07c Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 11:21:32 -0500
Subject: [PATCH 06/11] wip

---
 integrations/cli/index.test.ts | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/integrations/cli/index.test.ts b/integrations/cli/index.test.ts
index adce6e71bfe6..8705e81e7e22 100644
--- a/integrations/cli/index.test.ts
+++ b/integrations/cli/index.test.ts
@@ -2104,10 +2104,6 @@ test(
   },
 )
 
-function withBOM(text: string): string {
-  return '\uFEFF' + text
-}
-
 test(
   'CSS parse errors should include filename and line number',
   {
@@ -2120,8 +2116,7 @@ test(
           }
         }
       `,
-      'broken.css': css`
-        /* Test file to reproduce the CSS parsing error */
+      'input.css': css`
         .test {
           color: red;
           */
@@ -2130,8 +2125,12 @@ test(
     },
   },
   async ({ exec, expect }) => {
-    await expect(exec('pnpm tailwindcss --input broken.css --output dist/out.css')).rejects.toThrow(
-      /Invalid declaration.*at.*broken\.css:4:/,
+    await expect(exec('pnpm tailwindcss --input input.css --output dist/out.css')).rejects.toThrow(
+      /CssSyntaxError: .*input.css: 3:2: Invalid declaration: `\*\/`/,
     )
   },
 )
+
+function withBOM(text: string): string {
+  return '\uFEFF' + text
+}

From bb628d7cc95cc09c1b764298d7f30c71068dc7c4 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 11:38:11 -0500
Subject: [PATCH 07/11] Update error

---
 packages/tailwindcss/src/css-parser.test.ts | 2 +-
 packages/tailwindcss/src/css-parser.ts      | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index 78326661678e..500b08c7e91d 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -1193,7 +1193,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
        /* ^ Missing closing } */
         `),
       ).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 7:12: Missing closing } at .bar]`,
+        `[CssSyntaxError: input.css: 6:10: Missing closing } at .bar]`,
       )
     })
 
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index 4d6cd1a8a469..b22cf016e0a2 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -574,14 +574,14 @@ export function parse(input: string, opts?: ParseOptions) {
     if (parent.kind === 'rule') {
       throw new CssSyntaxError(
         `Missing closing } at ${parent.selector}`,
-        source ? [source, bufferStart, bufferStart] : null,
+        parent.src ? [parent.src[0], parent.src[1], parent.src[1]] : null,
       )
     }
 
     if (parent.kind === 'at-rule') {
       throw new CssSyntaxError(
         `Missing closing } at ${parent.name} ${parent.params}`,
-        source ? [source, bufferStart, bufferStart] : null,
+        parent.src ? [parent.src[0], parent.src[1], parent.src[1]] : null,
       )
     }
   }

From 84428689bbc5e745845cbffea5e9e7b7ad00ba38 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 11:45:28 -0500
Subject: [PATCH 08/11] fix off-by-one error

createLineTable really needs to be adjusted so everything is zero based instead of the current impl
---
 packages/tailwindcss/src/css-parser.test.ts | 16 ++++++++--------
 packages/tailwindcss/src/css-parser.ts      |  2 +-
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/packages/tailwindcss/src/css-parser.test.ts b/packages/tailwindcss/src/css-parser.test.ts
index 500b08c7e91d..5f0aa2287ae6 100644
--- a/packages/tailwindcss/src/css-parser.test.ts
+++ b/packages/tailwindcss/src/css-parser.test.ts
@@ -1164,7 +1164,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
             color: blue;
           }
         `),
-      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: input.css: 9:10: Missing opening {]`)
+      ).toThrowErrorMatchingInlineSnapshot(`[CssSyntaxError: input.css:9:11: Missing opening {]`)
     })
 
     it('should error when curly brackets are unbalanced (closing)', () => {
@@ -1193,7 +1193,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
        /* ^ Missing closing } */
         `),
       ).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 6:10: Missing closing } at .bar]`,
+        `[CssSyntaxError: input.css:6:11: Missing closing } at .bar]`,
       )
     })
 
@@ -1217,7 +1217,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
           }
         `),
       ).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 3:21: Unterminated string: "Hello world!"]`,
+        `[CssSyntaxError: input.css:3:22: Unterminated string: "Hello world!"]`,
       )
     })
 
@@ -1241,7 +1241,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
           }
         `),
       ).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 3:21: Unterminated string: "Hello world!;"]`,
+        `[CssSyntaxError: input.css:3:22: Unterminated string: "Hello world!;"]`,
       )
     })
 
@@ -1251,7 +1251,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       )
 
       expect(() => parseWithLoc('--foo')).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 1:0: Invalid custom property, expected a value]`,
+        `[CssSyntaxError: input.css:1:1: Invalid custom property, expected a value]`,
       )
     })
 
@@ -1261,7 +1261,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       )
 
       expect(() => parseWithLoc('.foo { --bar }')).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 1:7: Invalid custom property, expected a value]`,
+        `[CssSyntaxError: input.css:1:8: Invalid custom property, expected a value]`,
       )
     })
 
@@ -1283,7 +1283,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
           }
         `),
       ).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 3:19: Unterminated string: 'Hello world!']`,
+        `[CssSyntaxError: input.css:3:20: Unterminated string: 'Hello world!']`,
       )
     })
 
@@ -1293,7 +1293,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       )
 
       expect(() => parseWithLoc('.foo { bar }')).toThrowErrorMatchingInlineSnapshot(
-        `[CssSyntaxError: input.css: 1:7: Invalid declaration: \`bar\`]`,
+        `[CssSyntaxError: input.css:1:8: Invalid declaration: \`bar\`]`,
       )
     })
   })
diff --git a/packages/tailwindcss/src/css-parser.ts b/packages/tailwindcss/src/css-parser.ts
index b22cf016e0a2..3dd5e6ffe6cf 100644
--- a/packages/tailwindcss/src/css-parser.ts
+++ b/packages/tailwindcss/src/css-parser.ts
@@ -47,7 +47,7 @@ export class CssSyntaxError extends Error {
     if (loc) {
       let source = loc[0]
       let start = createLineTable(source.code).find(loc[1])
-      message = `${source.file}: ${start.line}:${start.column}: ${message}`
+      message = `${source.file}:${start.line}:${start.column + 1}: ${message}`
     }
 
     super(message)

From 34a21fcbd74e47fd723f8fe5806bf5c12bb6b2ac Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 11:50:58 -0500
Subject: [PATCH 09/11] fix

forgot to update the integration test
---
 integrations/cli/index.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/integrations/cli/index.test.ts b/integrations/cli/index.test.ts
index 8705e81e7e22..2a7547e10630 100644
--- a/integrations/cli/index.test.ts
+++ b/integrations/cli/index.test.ts
@@ -2126,7 +2126,7 @@ test(
   },
   async ({ exec, expect }) => {
     await expect(exec('pnpm tailwindcss --input input.css --output dist/out.css')).rejects.toThrow(
-      /CssSyntaxError: .*input.css: 3:2: Invalid declaration: `\*\/`/,
+      /CssSyntaxError: .*input.css:3:2: Invalid declaration: `\*\/`/,
     )
   },
 )

From 9bfa505085a84c280c8cffb9aa34b5957115943f Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 12:05:40 -0500
Subject: [PATCH 10/11] wip

---
 integrations/cli/index.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/integrations/cli/index.test.ts b/integrations/cli/index.test.ts
index 2a7547e10630..5f3b0fcb42ca 100644
--- a/integrations/cli/index.test.ts
+++ b/integrations/cli/index.test.ts
@@ -2126,7 +2126,7 @@ test(
   },
   async ({ exec, expect }) => {
     await expect(exec('pnpm tailwindcss --input input.css --output dist/out.css')).rejects.toThrow(
-      /CssSyntaxError: .*input.css:3:2: Invalid declaration: `\*\/`/,
+      /CssSyntaxError: .*input.css:3:3: Invalid declaration: `\*\/`/,
     )
   },
 )

From 061b1a530a9b4f08b0306312b3455559ff650804 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 10 Nov 2025 13:06:12 -0500
Subject: [PATCH 11/11] Update changelog

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 682b66628eb2..e44a8358a064 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Ensure validation of `source(…)` happens relative to the file it is in ([#19274](https://github.com/tailwindlabs/tailwindcss/pull/19274))
+- Include filename and line numbers in CSS parse errors ([#19282](https://github.com/tailwindlabs/tailwindcss/pull/19282))
 
 ### Added