For all panels is something like this:
<mx:Style>
Panel
{
borderColor: #cccccc;
backgroundColor: #cccccc;
themeColor: #cccccc;
}
</mx:Style>
This affects all panels, but here I have a couple of differents styles
<mx:Style>
myPanel1
{
borderColor: #cccccc;
backgroundColor: #cccccc;
themeColor: #cccccc;
}
myPanel2
{
borderColor: #cccccc;
backgroundColor: #cccccc;
themeColor: #cccccc;
}
</mx:Style>
To apply, select your panel, and in style select the desired style (or directly in mxml, add styleName="myPanel2" )
Jorge