Yes you would edit the style.css file inside of the theme itself (Epik in your case).
You should be able to simply hit the Reload button on your browser and that’s usually enough to clear the cache. If you’re sure you’ve cleared it and no changes are happening, then take a look at your code to make sure it changed. If it’s there and it’s still not working, then maybe the code needs adjusting.
It’s 1:30 AM on my end, so I’ll take another look at it tomorrow morning.
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