There are 2 versions, one for Mozilla browsers and one for WebKit & Opera.
Firefox & Flock
Once you have the Stylish extension installed, you can do install the following 2 themes into Stylish:
OS X Spinner for Google Reader
As userstyles.org restricts the file sizes of themes, the gReader css needed to be split over 2 themes. Once installed, you can update the theme in Stylish by going to Manage Styles > Find Updates.
If you normally view google through a domain other than .com (e.g google.it/…), you will need to change the @-moz-document source code at the top.
Camino
Add the following @import rule into the top line of your /Library/Application Support/Camino/chrome/userContent.css file, (or create it if it doesn’t exist).
@import url(greader.css);Place the greader.css file in the same chrome folder. The theme will be applied when you restart Camino.
Safari
The best method on Tiger is to install CreamMonkey, the Greasemonkey style plugin for Safari. Once installed, you will see a smiley in your menubar, then when you visit these 2 pages on userstyles:
OS X Spinner for Google Reader
You will see a ‘Load as User Script’ button. Click this, and then ‘install’ when the sheet appears. You’ll then just need to refresh gReader.
If you’re on Leopard, you’re better off using Safaristand and Pith Helmet to apply the custom css.
Be aware that SafariBlock may cause issues with the loading of the css - try disabling SafariBlock if you experience problems.
Omniweb
In Site Preferences > Page Appearance, choose the greader.css file under ‘Style Sheet’. The change should happen instantly!
Opera
Put the greader.css file anywhere you like! Right-click on the Google Reader page, choose "Edit Site Preferences" and select the CSS file through the display tab, under ‘My Style Sheet’. Like Omniweb, the change should apply immediately.