Hello team Anima,
If you export a project to HTML it is responsive to different screen sizes.
React? Not the case, it will stay stuck on one screen no matter what screen size you change to.
Hey @Tom1 thanks for writing. You are correct in the fact that Media Queries (breakpoints) are automatically added to your exported HTML code, whereas React is exported separately. Here’s a helpful video and article that will explain to developers how to add the media queries manually to your React code, I hope it helps 
!