You need to change the HTML to point to the tsx file too: <script type="module" src="./index.tsx"></script> There are ambient TS definitions for CSS Modules,

You need to change the HTML to point to the tsx file too: <script type="module" src="./index.tsx"></script> There are ambient TS definitions for CSS Modules, it just had a bug in 1.0.0 - fix is merged and will be released shortly.