I am not sure what designer thought it would be a good idea to implement this area of Rollbase v2.0 in a custom styling, when the whole of the rest of the product uses the much more elegent and mature Bootstrap style - but please don't let that person make any more changes to the interface and make Rollbase any more bastardised than they just did.
There are perfectly good Bootstrap components for this area of Rollbase without having to try and re-invent wheels unnecessarily and of a lower quality.
Note the prepend and append buttons and dropdowns for the search input is much more elegant:
I suggest that by sticking with the standard framework it will be better for people wishing to choose their own Admin theme, eg:
I have added some further enhancement suggestions here:
Thanks for sharing your feedback. We have passed it to our user experience team and product management team for consideration.