This is a fairly simple but effective way to highlight documents in a view.
Insert a column at the beginning of your view, hide it and ensure the column option "Use Value as Color" is checked. In the formula for this column, add the following color definitions (or make your own based on the RGB scheme).
red := 255:0:0;
black := 1:1:1;
After the colors are defined, add a line of code like the one below. In this example, if the field AssignmentTargetDate is blank, then set this column to contain the RGB code for red, otherwise, leave it as black.
@If(AssignmentTargetDate = "";red;black)
When the view is displayed, any rows which have a blank AssignmentTargetDate will be displayed with red text. You can get as complex as you can with your color logic, but the simplicity of this feature is what makes it so effective.