Very nice, especially the focus bar! I hope the xml wasn't too painful.
I think the darker area is the "glass" overlay for the level and experience text. You can remove it by adding the following code where blank.tga is a fully transparent graphics file. You can use that trick for other graphics as well. You might want to look at Black Vellum Toolbars for examples.
Code:
<Mapping ArtAssetID="letterbox_bottom_glass_overlay" FileName="blank.tga" />