Highlight selected column

When looking at the data sheet and clicking the column header label, the selected column details are displayed in the details view below. The users are getting lost because there is no indication which column is selected.

Update the sheet viewer so that currently selected column is highlighted as follows:

1. If not mapped (RDF term is blank): Yellow
2. If mapped (RDF term is not blank): Pink

For unselected columns, the background should be:

1. Not mapped: default (as is now)
2. If mapped: Light blue