What is a good way to add dark theme support for plugins?

sphinxcontrib-mermaid embeds a theme-independent transparent svg. As a result, black lines and black text vanish on the dark background of the dark pydata-sphinx-theme.

What is the best approach to fix this issue? Options:

• is it ok/recommended to add special CSS for that plugin at pydata_sphinx_theme/assets/styles/extensions - a solution similar to https://github.com/pydata/pydata-sphinx-theme/blob/main/src/pydata_sphinx_theme/assets/styles/extensions/_graphviz.scss would work
• or is that something that should be addressed on the side of /sphinxcontrib-mermaid