Explorer CSS Improvements

[ymittal]

Thanks for this amazing tool!

I'm on v0.17.5 and it seems like the explorer CSS needs some work

• could add left padding so that the checkbox is not cut off
• padding around the option to select Query/Mutation/etc

[pavelloz]

@ymittal hey how did you manage to install graphiql-explorer with react 17?
Whenever i try to upgrade my project's dependencies i get a bunch of errors about incompatible dependencies, one of them is:

npm WARN Could not resolve dependency:
npm WARN peer react@"^15.6.0 || ^16.0.0" from [email protected]
npm WARN node_modules/graphiql-explorer
npm WARN   dev graphiql-explorer@"^0.6.3" from the root project

Which drove me here to file an issue to maybe take a look at it.