My take on H2O.ai UI Engineering Coding Challenge
run $ npm run dev to run development environment
run $ npm run build to build the solution, output will be waiting ing public folder, so go ahead and give that index.html a double click
run $ npm run test to run the tests of the app
Assignment with clarifications
Tests - brief is fine, i.e. doesn't need to be exhaustive. Just one or two tests that demonstrate your preferred approach to testing is just fine.
Scroll bar - no need to replicate; default is fine.