[feat]: update dev script (#3)

Package version bumped to 1.0.0 and updated dependencies in lock file. Replaced `concurrently` with `npm-run-all` in development script. Added support for `npm-run-all`. Removed redundant CSS class and added new CSS class.

[chore]: bumped package version (#2)

The version number in package.json was incorrect. This PR corrects the version number from 1.0.0 to 0.0.1.