Markdown Themed Images
This extension adds support for "themed images" in the VS Code markdown preview. In particular, you can append #gh-light-mode-only or #gh-dark-mode-only to the end of an image's URL, and that will hide/show the appropriate images based on the end-user's active theme (Details).
For example, the following GitHub logo will toggle its fill color based on the active VS Code theme (dark vs. light):
