As of v.33.0.1706.0, Chrome Canary no longer supports custom stylesheets in the User Stylesheets directory.
@darcyclarke filed an issue to restore this functionality. Feel free to voice your opinions there.
In the interim, @mauricecruz has a solution injecting styles through the inspector's inspector.
Zero Base Themes
I've started moving this theme across to:
A third version of the theme I tweaked, changing the toolbar icons to text and fixing an issue with the latest release of Chrome Canary.
rake to copy the files to the correct locations.
Find your Chrome's user stylesheets directory:
Mac - Finder > shift + cmd + g:
~/Library/Application Support/Google/Chrome/Default/User StyleSheets/
Mac - Terminal:
~/Library/Application\ Support/Google/Chrome/Default/User\ StyleSheets/
C:\Users\**Your Username**\AppData\Local\Google\Chrome\User Data\Default\User StyleSheets\
Replace the existing "Custom.css" file with this one
No restart needed, changes are applied immediately
IR_Dark_Monokai Designed and developed by Andres Pagella: http://www.andrespagella.com/customising-chrome-devtools
Ben Truyman, Todd Werth: http://blog.toddwerth.com/entries/2
Toolbar code by Harris Novick: https://gist.github.com/4316646
Inspired by Darcy Clarke's blog post: http://darcyclarke.me/design/skin-your-chrome-inspector/
Dock-To-Right when using vertical splitting: https://github.com/mauricelam/DockToRight
Automatic rake file by Rodolfo Puig: https://github.com/simonowendesign/SO-Dark-Monokai-v3/pull/21