Brings back the old line-height, colors, padding, borders, etc. of StackExchange websites like StackOverflow, SuperUser, ServerFault, etc.

PLEASE UPDATE SCRIPT (Sep 24th): updated script to reflect new changes to code blocks

If you only want the old line-height back, use this script: https://github.com/CertainPerformance/Stack-Exchange-Userscripts/tree/master/Compact-Line-Height

I also have a Google Chrome Extension and Stylish Theme for this :)
Check out the GitHub repo: https://github.com/Prid13/Revert-StackExchange-Formatting