Fix and improve implementation

[w-masahiro-ct]

The existing implementation contains JavaScript syntax.
It appears to be miraculously working without issues because the JavaScript split syntax is being interpreted as a range in Ruby.
Therefore, I have fixed the implementation.
Additionally, I have improved performance and refactored.

[gjtorikian]

Oh, that’s embarrassing! 🫣 Thanks for fixing that typo, too.

Since Tailwind 4 was just released, I will need to do a version bump to support it—and this patch will be included when that’s ready. Thank you very much for your contribution. 🙇🏻

[w-masahiro-ct]

@gjtorikian This pull request has a slightly large diff.
Therefore, would it be possible to release it as v0.16.0?
I think releasing Gem that supports Tailwind 4 as v0.17.0 or v1.0.0 would be a good approach.

I'm looking forward to this Gem supporting Tailwind 4, thank you!!

[gjtorikian]

Yes, I suppose you’re right. Maybe people will use Tailwind 3 for a long time and will want these updates separate from Tailwind 4. 🤔

[david-uhlig]

I haven't investigated deeply, but glancing over the upgrade guide it looks like you might be able to support v3 and v4 at the same time. Otherwise, maybe a configuration option and separate parsers for v3 and v4 would make sense?