You'll be fine. If anything CSS is the one thing that's gotten easier in web dev. It might take some time but you'll be able to grok it for sure if you've dealt with old school CSS.
Easier? Well, even if you don't have to deal with legacy styling (which had moments of insanity, like floats, and other things which were fairly reasonable, like tables, br, b, i), there is so much new CSS to replace the old: variables, transforms, complex animations, using borders to make arrows and other visual content, in flow vs out of flow, container queries, view transitions api, px, pt, em, rem, vh, vw, query units, initial vs inherit, vs unset vs revert, new color formats, a million new properties for the complexity of interactivity with the gamut of user agent form factors
You know what? I'm going to stop because the list goes on and I don't even think I touched on 1% of the "new" CSS
These days I mostly just use tailwind. It gives me a sane, easy to work with api, and the updates are a more manageable trickle than a deluge