Change colour of browser address/search bar In OSX would it be possible to change the background colour and/or text colour of the address/search bar input field of a browser (Chrome, Safari, etc)? Not just the highlight colour (System Prefs > General > Highlight color) but as a permanent colour change, independent of focused or highlight state. 

Mock up attached.

I'm completely new to OSX/app development and have no idea if this style setting made in the operating system or in the browser app? (Or if it's even possible to change at all). 

I'm currently interested in the possibilities of how to achieve this - with the ultimate end goal to be able to toggle the override on or off when necessary.
The Search Bar highlight colour is controlled by a System Preference.



System Prefs > General > Highlight color 



This works for Safari &amp; Chrome - though it also changes your highlight system-wide.