Redmine

When I see project page in italian language very long menu, on right side, appairs like white text on white background (see attachment).
Page width is lesser than menu width, expecially for empty project.

Environment:
Redmine version 2.3.1.stable
Ruby version 1.9.3 (i686-linux)
Rails version 3.2.13
Environment production
Database adapter MySQL
Redmine plugins:
no plugin installed