Is separating keywords with hyphens SEO-friendly?

Sometimes, when we use long words in our content, it doesn't fit the screen. That's especially true with headings and mobile screens. In some cases, they get unnecessarily big, with half of the screen being blank. I thought about automatically hyphenizing them using CSS. My question now is, will this affect SEO? As far as I understand, CSS is just the visualization for the visitor. So, I assume crawlers should still be able to recognize the whole words, even if they are hyphenized, am I right?

Great question, I want to know too.

True, CSS is generally visual only, having little to none effect on SEO directly. (lot of indirect effects though)

CSS can insert an actual text with use of ::before or ::after. This text would be in the end-result render and crawl-able by bots like the rest of the text.

In such case it could influence the rankings.

Using hyphens is very common in URLs but not so much in text. Hard to say how it will be received by engines.

It's very possible they will simply be ignored.

Search for your keyword as is and note down the results. Then search for your keyword with hyphens and note down those as well. If they are very different, engines consider them difference search queries.

I did a few experiments and results where always almost identical.

So you should be good.

Imo Google replaces hyphens with spaces for the most part

Yes, you'll be ok using hyphens