If the trim you've added isn't enough, you may want to consider adding additional layers. For example, laying molding directly on the face of molding can create a raised look, and once finished, can still appear to be a single combined molding piece.
When deciding to add additional molding, you might consider adding a plinth block. A plinth block is usually a decorative piece of molding that can look like the base of a column when used at the bottom of a door. You can also use plinth blocks as part of a fireplace surround, or in this case, at the top of a door. The additional molding will run right into the plinth block, creating a nice finished edge.
