If you find the Mac OS 10.14 dark mode too dark, there is a fix.
Open 'System Preferences'
Click on 'General' and change the 'Appearance' option to 'Light'
Open Terminal inside the Utilities folder, and paste in:
defaults write -g NSRequiresAquaSystemAppearance -bool true
Log out, or restart.
Dark mode will now only show for the menubar and the dock. The rest of the windows will be white (Like in Mac OS 10.13 High Sierra).
If you want to put it back, paste this in the terminal and then logout or reboot:
defaults write -g NSRequiresAquaSystemAppearance -bool false