Unique selectors for library styling

[himynameisdave]

Working in a larger codebase, you're likely to have a .flex class already. Libraries like this should user something more unique to ensure that there isn't an unintended inheritance.

I'm partial to [data-*] selectors, but a scoped class like svelte-flex__flex would work.

Ideally, it should be a selector which svelte can mangle into something smaller at compile time.

Taken from this comment.

[himynameisdave]

This is resolved by #22, since now we just use style directives and no .flex class.