Disclaimer: the last time I used Telerik components was in ASP.net 2.0 about 9 years ago.

For React: http://material-ui.com/#/

Bourbon + Refills: http://refills.bourbon.io/

Material Design Lite: http://www.getmdl.io/

Bootstrap: http://getbootstrap.com/

etc, etc. Even back when I used telerik components, it was often faster to develop my own component, tailored to use-case, than it was to figure out how the hell to customize the 15-deep DOM tree that a table component generated.