Transparent images broken with regular []() tags but not with [bg]()

[ymollard]

I made an example code to demonstrate that issue:

Deployment: https://candid-tulumba-47300d.netlify.app/
Code: https://gitlab.com/ymollard/test-marp-img-bng/-/blob/main/index.md

Expected behaviour: transparent background for both Python logos using the []() tag and [bg]()
Actual behaviour: transparent background only for [bg]() but not for []().

[yhatt]

Aren't you using Marp Core's default theme?

default theme has an inherited style from GitHub's Markdown rendering. Markdown images in GitHub by ![]() actually has colored background inherited from GitHub's background.
https://github.com/sindresorhus/github-markdown-css/blob/b3977a0367f753d1c58812c4218f69f013504c51/github-markdown.css#L216-L221

You can tweak the style within Markdown to remove inherited background color:

<style>
img {
  background-color: transparent;
}
</style>

Related

• No parsing of transparent background for PNG images #196 (comment)
• Transparent background of png image in header is rendered with a white background marp#345

[ymollard]

Yes, theme: gaia works properly but the default does not. The manual img {} also fixes the issue.
So if I understand well, it's not a bug, it's a feature, so I close that issue.
Thanks for the fast and complete answer!