Merge pull request #735 from marp-team/firefox-enable-context-properties

Fix incorrect page number rendering in `uncover` theme on PDF rendered by Firefox

Author: yhatt

CHANGELOG.md

@@ -12,7 +12,9 @@
 ### Fixed
 
 - Improve CLI boot time by loading Marpit and Puppeteer on demand ([#732](https://github.com/marp-team/marp-cli/pull/732))
-- `gaia` theme renders an incorrect PDF background when using Firefox browser (`--browser firefox`) on macOS ([#734](https://github.com/marp-team/marp-cli/pull/734))
+- Improve PDF rendering compatibility with macOS Firefox (`--browser firefox`)
+  - Fixed: `gaia` theme renders an incorrect PDF background ([#734](https://github.com/marp-team/marp-cli/pull/734))
+  - Fixed: `uncover` theme renders incorrect page numbers ([#735](https://github.com/marp-team/marp-cli/pull/735))
 - Mitigate slow PDF rendering of `gaia` theme on macOS/iOS when generated via Chrome/Chromium ([#734](https://github.com/marp-team/marp-cli/pull/734))
 
 ## v4.4.1 - 2026-07-04

src/browser/browsers/firefox.ts

@@ -14,6 +14,12 @@ export class FirefoxBrowser extends Browser {
       await this.generateLaunchOptions({
         ...opts,
 
+        extraPrefsFirefox: {
+          // https://github.com/marp-team/marp-core/pull/424#discussion_r3605672166
+          'svg.context-properties.content.enabled': true,
+          ...opts.extraPrefsFirefox,
+        },
+
         // NOTE: Currently Windows path is incompatible with Puppeteer's preparing
         // FIXME: CircleCI does not work custom user data directory
         userDataDir:

src/converter.ts

@@ -122,7 +122,6 @@ export class Converter {
   readonly options: ConverterOption
 
   private _sOffice: SOffice | undefined = undefined
-  private _firefoxPDFConversionWarning = false
   private _experimentalEditablePPTXWarning = false
 
   constructor(opts: ConverterOption) {
@@ -342,16 +341,6 @@ export class Converter {
     const ret = file.convert(this.options.output, { extension: 'pdf' })
 
     // Generate PDF
-    const browser = await this.browser
-
-    if (browser.kind === 'firefox' && !this._firefoxPDFConversionWarning) {
-      this._firefoxPDFConversionWarning = true
-
-      warn(
-        'Using Firefox to convert Markdown: The output may include some incompatible renderings compared to the output generated by Chrome.'
-      )
-    }
-
     let outlineData: OutlineData | undefined
 
     ret.buffer = Buffer.from(

test/converter.ts

@@ -931,37 +931,6 @@ describe('Converter', () => {
           timeout
         )
       })
-
-      describe('with Firefox browser', () => {
-        it(
-          'outputs warning about incompatibility',
-          async () => {
-            const warn = jest.spyOn(console, 'warn').mockImplementation()
-
-            await using browserManager = new BrowserManager({
-              finders: ['firefox'],
-              timeout,
-            })
-
-            await pdfInstance({
-              getBrowserManager: () => browserManager,
-              output: 'test.pdf',
-            }).convertFile(new File(onePath))
-
-            expect(warn).toHaveBeenCalledWith(
-              expect.stringContaining(
-                'The output may include some incompatible renderings'
-              )
-            )
-            expect(fs.promises.writeFile).toHaveBeenCalled()
-
-            const [lastCall] = writeFileSpy.mock.calls.slice(-1)
-            expect(lastCall[0]).toBe('test.pdf')
-            expect(lastCall[1]).toBeInstanceOf(Buffer)
-          },
-          timeout
-        )
-      })
     })
 
     describe('when convert type is PPTX', () => {