Source: Webkit.org
The version of WebKit that ships with Safari 3.1 on Windows uses CoreGraphics antialiasing for text. The latest WebKit in nightly builds has made good progress on a GDI text rendering mode (i.e., the text rendering matches your OS look/settings). We encourage Windows testers to try out GDI text rendering and file bugs that you find at http://bugs.webkit.org/.
To enable GDI text rendering, you will need to hand edit your preferences file, as there is no visible UI option in Safari 3.1 for this. You will need to set WebKit’s “WebKitFontSmoothingType” preference to a value of “4″.
The preferences file on Windows XP is:
C:\Documents and Settings\<username>\Application Data\Apple Computer\Safari\WebKitPreferences.plist
On Vista, it is:
C:\Users\<username>\AppData\Roaming\Apple Computer\Safari\WebKitPreferences.plist
The values that are listed in Safari’s UI for this preference map to the numbers 0-3.
Note that while you can turn on GDI text rendering in the WebKit that ships with Safari 3.1, most advanced text features will not work. These include stroking and filling text, most advanced text features in SVG, shadows, partially transparent text (rgba/hsla) and text inside a transparency layer (opacity). All of these features should work now in the latest nightlies.
If you have changed the setting in Safari you may have to edit that preference file. It can be found at:
%APPDATA%\Apple Computer\Safari\Preferences\com.apple.Safari.plist