I am sorry, but your screen is not affected by kitkat.
What you are looking for is a dark background and the brightness slider. and/or a new battery
Dude I have tried almost all KitKat ROMs I also got new battery and I always set black wallpapers and brightness level to 0 still can't get 3 hours screen time that's why asked for best battery KitKat ROM and I'm using a OEMbattery which cause screen flicker after 10%
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15 Sep 2014
By Conan Troutman
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?