Provide better options for styling - particularly nested elements

**Affected Projects**
React

**Is your feature request related to a problem? Please describe.**
This is a great library overall, so it's a shame it appears handicapped regarding fine-grained and intuitive options for styling.
E.g. I need to provide inline styling to the input element of a CategorySearch component. This is so I can pass the `color` property as a variable based on my app's active theme (e.g. if dark mode is active, the searchbar should show white text, and vice versa).
As far as I'm aware this is not possible right now. If I provide the style prop to CategorySearch, the `color` attribute is applied to the wrapper but does not change the text color of the input element it wraps (even when adding `!important`). Providing a class name is also pointless because I can't control the theme variable inside a CSS stylesheet.

**Describe the solution you'd like**
A simple inline-styling solution for every component; not just the wrapper, but also every child element inside it.

**Describe alternatives you've considered**

**Additional context**