Got a few complains about this already from Opera users.
While I don't care much about Opera, since it's not open source and doesn't uses webkit, somebody else could patch this up.
We have a function (that we mainly use for the header menu navigation icons): while you hover over an image that has the class "lighten", it gets brighter.
Besides the graphical effect not working in Opera, it also makes the images unclickable, making navigation harder.
The fixed code will also be used on FreezingMoon.org
Fix issue #1 "Image lighten not working in Opera"