If you have a Samsung mobile device...
S3, s4, s5, note3, or note4 do this....
Settings
Device
Accessibility
Direct Access
Turn on direct access, this will enable three selectable options.
Select Negative Colors.
Exit configuration.
To use your new option, click your home button 3 times and your screen will go to negative colors. Open your browser and you will now have white text on black background (high contrast). Makes it easy to see text in the dark and saves on power.
To return things back to normal mode, click home again 3 times and like Dorothy and Toto, you will be back home with the old settings. 4951