How to use FSCSS with CSS

I don't want to write too much CSS NOTE, so I need some shorthand methods that will reduce my time.
help:

<style>
//FSCSS here
</style>
<script  src="https://winiss.tiiny.site/scripts/fscssv3.1m.js"></script>
<script src="https://winiss.tiiny.site/scripts/m.js"></script>

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