a system includes a glare - blocking member including a left recess , a right recess , and a rail including , a left lateral portion including a left protrusion configured to mate with the left recess of the glare - blocking member , a right lateral portion including a right protrusion configured to mate with the right recess of the glare - blocking member , and a projecting contour disposed between the left and right lateral portions , wherein an apex of the projecting contour is disposed farther from a line passing through lower edge portions of the rail than is either the left or the right protrusion .