I wouldn't use solutions such as Perfect Scrollbars. Perfect Scrollbars, for example, disables native scrolling feature of the browser (overflow: hidden) to add its own <div /> tags mimicking a scrollbar and adding !important rules while using very low specificity CSS selector names. It could cause issues if you used the same class name ps-container in your app. Ignoring the class name issue for now, on fast machines, this is okay'ish but on slower machines, scrolling feels laggy and on mobile it's (almost) impossible to scroll. <Edit> But luckily on Mobile we have a drag gesture. That's why nobody really complains about scrolling on mobile.</Edit>

I suggest to style scrollbars only on platforms and browsers which support it natively, ​not to impact the UX on other platforms and browsers.​

Agreed with @fibric, solutions like perfect scrollbars always have hiccups in the performance as they override the native scrollbar behaviour.

So CSS scrollbars is a good idea if you’re okay with the lack of support in some browsers. Since it is styling the native scrollbars, the performance won’t be affected.

My experience when working on large projects for "late adopter" users, i.e. people with very little experience with internet: When presented with heavily styled or non-standard versions of native elements (like form fields or scrollbars) they often ignored them or weren't able to use them.

So my advice is, don't style them unless really necessary. And if you do, don't overdo it.

If you plan to style the scrollbars for aesthetic reasons, don't even bother doing that. User's don't really care about how the native elements look, they are used to them. Also, most users these days won't even see the scrollbars - in most browsers, and especially on mobile platforms, scrollbars are hidden and will only appear when actively used.