[Radiance] Font of window title is not rendered correctly

Using Radiance, the font of window title and menu titles is not rendered correctly (both global and local title and menus). The letters have some kind of glow around them. Also the font of the panel indicator (Date and Time) is affected. This doesn't exist using Ambiance.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: light-themes 14.04+14.04.20140311.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-17.37-generic 3.13.6
Uname: Linux 3.13.0-17-generic x86_64
ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Mar 18 11:34:25 2014
InstallationDate: Installed on 2014-03-08 (9 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140304)
PackageArchitecture: all
SourcePackage: ubuntu-themes
UpgradeStatus: No upgrade log present (probably fresh install)