Responsive GitHub user search using React & TypeScript w/themes

Any constructive feedback is welcome.

In particular, I'd be interested in knowing ways to improve the structure of my app. Specifically, I'd like to know what components you would break it into, where you would keep the styling, any libraries/hooks you would recommend/leave out, how you'd solve the problem of implementing the light/dark themes, etc.

Also, just any comments on best practices regarding React, TypeScript, HTML, or CSS, or tips on improving code maintainability/readability would be great.