Java Development Tools

I'm trying to create a panelBox with a large header, however my styles are being overriden by an inline style that I don't know the source of.

My style rules look like :

af|panelBox::header {
    height: 2em;
}
af|panelBox::header-start {
    height: 2em;
}

af|panelBox::header-center {
    height: 2em;
}

af|panelBox::header-end {
    height: 2em;
}

Using Firebug I can see that these are being set on the correct element, however they are being overriden by 'height: 25px' that is added as an inline style on the div/table elements that represent the panelBox header. Where does this 'header: 25px' come from? (it's not present anywhere in my project) Does the header bar for panelBoxes have to be 25px tall?