Modify Chrome user agent stylesheet [duplicate]

I would like to modify Chrome's user agent stylesheet. I am not looking for how to override them with CSS. I want to modify the default values and add some new rules that would help me speed up my workflow and enhance my browsing experience.

Please also I am not looking for an extension that would do this job for me.

1 Answer

For Chrome v32 and below:

1. In Google Chrome, go to URL about:version and take note of the "profile path".
2. Browse to the profile path in your file browser. Inside your profile folder, open the User StyleSheets folder. Inside "User StyleSheets", there should be a file called Custom.css, empty by default.
3. Just add your styles in Custom.css.