Hello,
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
"plotly_dark" Theme
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:
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?