[win32 CSS theme] Fix a small syntax error
On Windows with GTK_THEME=win32 and CSD enabled I get this error message:
Gtk-WARNING **: 15:51:28.177: Theme parsing error: gtk-win32-base.css:1043:59: Junk at end of value for background-image
Fix that.
On Windows with GTK_THEME=win32 and CSD enabled I get this error message:
Gtk-WARNING **: 15:51:28.177: Theme parsing error: gtk-win32-base.css:1043:59: Junk at end of value for background-image
Fix that.