Heatmap Custom Hover Template


There appears to be an issue when using a custom hovertemplate with heatmaps on certain themes. If using the extra tag, the text is almost impossible to see when using the “plotly_dark” template. Example below:

"none" Theme
Screen Shot 2021-10-10 at 8.12.19 PM
"plotly_dark" Theme
Screen Shot 2021-10-10 at 8.12.03 PM

So far, I’ve tried modifying all the hoverinfo properties but this only affects the aspects of the hovertemplate not contained in the extra tag. In my example that would be the “Mileage: 28” as shown below:
Screen Shot 2021-10-10 at 8.22.59 PM
I also tried modifying the color using a span tag as detailed in this post, but just like above, it has no effect on anything inside the extra tag.

Typically, anything inside the extra tag matches the marker/line color of the trace you are hovering over, but I’m not sure how this applies to heatmaps. Is there anything else to try? Or this just a current limitation of the heatmap figures?

Any thoughts on this? I also tried printing the full_figure_for_development(), but could not find a parameter that was changing background or text colors in the extra tag.