Chrome 130 doesn't generate correct PDF slides for Marp themes with the text-shadow and custom background

[polarnik]

Version of Marp Tool

@marp-team/marp-cli v4.0.0 (w/ @marp-team/marp-core v4.0.0)

Operating System

macOS

Environment

• OS version: macOS Sonoma 14.5
• Node.js version: Marp CLI 4.0.0, Node.js v22.10.0
• Chrome: Version 130.0.6723.117 (Official Build) (arm64)

How to reproduce

1. Create a theme with the text-shadow effect, like

:root {
    --bg-color: #000000;
}
section {
    text-shadow: 1px 1px 5px var(--bg-color), 0px 0px 5px var(--bg-color), 1px 2px 10px var(--bg-color), -1px -1px 10px var(--bg-color), 2px 3px 10px var(--bg-color);
 }

3. Generate HTML slides

4. Generate PPTX slides

5. Generate JPEG slides

6. Generate PDF slides

7. Create a theme with the text-shadow effect and some background color or background image, like

:root {
    --bg-color: #000000;
    --blue: rgb(84, 104, 237);
    --green: rgb(211, 221, 80);
}
section {
    text-shadow: 1px 1px 5px var(--bg-color), 0px 0px 5px var(--bg-color), 1px 2px 10px var(--bg-color), -1px -1px 10px var(--bg-color), 2px 3px 10px var(--bg-color);
 }
strong {
    background-color: var(--blue);
    font-style: normal;
}
em {
    background-color: var(--green);
    color: var(--bg-color);
    font-style: normal;
}

8. Generate HTML slides
9. Generate PPTX slides
10. Generate JPEG slides
11. Generate PDF slides

Expected behavior

3-6. Texts will have a small shadow, but not the strong solid background
8-11. Texts will have a small shadow, but not the strong black background

Actual behavior

3-6. Texts have a small shadow for HTML, PPTX, JPEG, PDF formats
8-10. Texts have a small shadow for HTML, PPTX, JPEG formats

11. Texts have the strong black solid background for the PDF format

Additional information

It is a Chrome issue. It worked well two years ago with Chrome 100, but not now.
The workaround is -- don't use background-image or background-color with the text-shadow. I don't use the text-shadow anymore, because I would like to use some backgrounds

[yhatt]

It's a known bug of Mac's PDF rendering, such as Preview.app, Quick Look in Finder, and so on. Check out this issue:
https://issues.chromium.org/issues/41476907

The rendered PDF should show as usual in third party PDF viewers like Adobe Acrobat, Google Chrome (pdf.js), etc.

<style>
:root {
    --bg-color: #000000;
}
section {
    text-shadow: 1px 1px 5px var(--bg-color), 0px 0px 5px var(--bg-color), 1px 2px 10px var(--bg-color), -1px -1px 10px var(--bg-color), 2px 3px 10px var(--bg-color);
 }
 </style>

# Hello

marp markdown.md --pdf

Output PDF

Mac Preview.app	Adobe Acrobat

Marp cannot fix that because it is caused by upstream.