Problems adding a custom header to RT 4.0.2


I created a callback (at
/opt/rt4/local/html/Callbacks/My/Elements/Header/Head) to include a custom
Header on my rt instance, but when I open rt on the browser (firefox 6), the
main navigation menu is on top of my header. Is that expected?

I am currently trying to change the css files (layout.css and nav.css) to
fix this issue, but I am not sure this is the right way to go (and it is
giving me a lot of trouble - no css joy here).

I am using the default theme (aileron).

Best regards,