UI for ASP.NET Core
The Telerik UI for ASP.NET Core HeatMap component has several built-in themes and swatches you can chose from. Explore the Default (our own styling), Material (based on the Material Design guidelines), Bootstrap (which looks like the Bootstrap styling to integrate better) and Fluent (based on Microsoft Fluent UI) themes and choose the swatch that meets your design requirements.
If neither of the available themes and swatches satisfies your needs, you can easily customize them with a few lines of CSS or create new themes by using the Progress SASS ThemeBuilder application.