[Bug] When saving a page served via `file:///`, `1.22.98.XPI` does not include the CSS in the self-extractable zip file.

[roke-julian-lockhart]

What The Problem Is

When saving a page, SingleFile does not include the CSS3 markup, of pages served over file://localhost/, in its resultant self-extractable zip archive: ¹

Screencast_20260628_181817.webm

How To Reproduce It

1. #!/usr/bin/env pwsh
   firefox-nightly about:support

2. Save the file, via the native option, as a "Complete webpage" (XHTML).

3. When .assign'd to "file:///$Home/Downloads/Troubleshooting%20Information.xhtml", invoke SingleFile.

4. When .assign'd to "file:///$Home/Downloads/Troubleshooting%20Information%20(28_06_2026%2017%EF%BC%9A31%EF%BC%9A41).u.zip.html" (via "moz-extension://$UUID/src/ui/pages/viewer.html?compressed&blobURI=blob:moz-extension://3d005895-683a-4b99-96d7-f6e887bf859d/316c67e0-b37d-42f1-862f-a42b54c5e235"), you shall observe that no CSS was incorporated.

Environment

• OS

  1. Details

     #!/usr/bin/env pwsh
     $OSRelease = [Ordered]@{}
     Get-Content /etc/os-release | ForEach-Object {
     	If ($_ -Match '^\s*([^=]+)=(.*)$') {
     		$Name  = $Matches[1]
     		$Value = $Matches[2]
     		If ($Value -Match '^"(.*)"$') {
     			$Value = $Matches[1]
     		}
     		If ($Value -Match '^[0-9]+$') {
     			$Value = [Int64]$Value
     		}
     		$OSRelease[$Name] = $Value
     	}
     }
     [PSCustomObject]$OSRelease |
     	Select-Object NAME, VARIANT, VERSION_ID |
     	Format-List |
     	yq -P

  2. NAME: Fedora Linux
     VARIANT: KDE Plasma Desktop Edition
     VERSION_ID: 44

• Browser

  1. Details

     #!/usr/bin/env pwsh
     rpm -qf (Get-Command firefox-nightly).Source --queryformat @'
     Name: %{NAME}
     Version: %{VERSION}
     Release: %{RELEASE}
     Architecture: %{ARCH}
     Install Date: %{INSTALLTIME:date}
     Size: %{SIZE}
     Signature: %{SIGPGP:pgpsig}
     Source RPM: %{SOURCERPM}
     Build Date: %{BUILDTIME:date}
     Build Host: %{BUILDHOST}
     Packager: %{PACKAGER}
     Vendor: %{VENDOR}
     '@ | yq -P

  2. Name: firefox-nightly
     Version: 154.0a1
     Release: 20260626040954
     Architecture: x86_64
     Install Date: Sat 27 Jun 2026 10:51:17 BST
     Size: 396878436
     Signature: (none)
     Source RPM: firefox-nightly-154.0a1-20260626040954.src.rpm
     Build Date: Fri 26 Jun 2026 11:08:33 BST
     Build Host: f41304c69f6d
     Packager: (none)
     Vendor: Mozilla

Additional Context

In lieu of issues/1494, I know of no alternative to this process.

Footnotes

1. user-attachments/files/29440941/Troubleshooting.Information.28_06_2026.18.18.39.u.zip.html ↩