This is a plugin, for showing the post and comment heat map like Github Contribution Graph.
1. add <div id="hi_heatmap" class="hi_heatmap"></div> to where you want to show the heatmap. eg: theme's sidebar.php file.
2. optional, modify the css file, fit with your theme.
3. optional, make sure the theme you using with the <?php wp_footer() ?> in footer.php or other php file.<h3>Thanks</h3> 1. https://biji.io/
2. https://picocss.com/docs/tooltips.html
3. Github contributions