- Quit Safari and navigate to /Applications/Safari.app with the Finder (or better PATHFinder)
- Control-click (or right click) on Safari.app and select Show Package Contents from the pop-up menu
Navigate into Contents » Resources
- A good idea is to first make a copy of the following four files to serve as a backup:
AW_ActiveTabCenterFill.png,AW_ActiveTabLeftCap.png, AW_ActiveTabLeftCapFirstTab.png, AW_ActiveTabRightCap.png
- Edit these AW_ files in your image editor of choice, fill/change the color to whatever you like!