Set Scroll Bar style for Individual Application in OS X

defaults write NSGlobalDomain AppleShowScrollBars -string "Always"
defaults write NSGlobalDomain AppleShowScrollBars -string "WhenScrolling"
defaults write NSGlobalDomain AppleShowScrollBars -string "Automatic"

ProTip™: It's recommended to set Always for web browers if you are developing web pages on a track-pad-only macOS device as you may be suprised at how crappy your scrollable containers look like.

defaults write com.google.Chrome AppleShowScrollBars -string "Always"
defaults write com.google.Chrome.canary AppleShowScrollBars -string "Always"
defaults write org.mozilla.firefox AppleShowScrollBars -string "Always"
defaults write org.mozilla.firefoxdeveloperedition AppleShowScrollBars -string "Always"
defaults write org.mozilla.nightly AppleShowScrollBars -string "Always"
defaults write org.mozilla.tor\ browser AppleShowScrollBars -string "Always"

• https://gist.github.com/tylerwalts/9375263