An apparatus includes first, second, and third glass portions, with the third glass portion between the first and the second, where the first, second, and third glass portions are configured in spaced relation from each other. The third glass portion is substantially parallel to the first glass portion. A light source emits light into the third glass portion via an edge of the third glass portion. Light-scattering structures scatter at least a portion of the light emitted by the light source into the third glass portion in a direction substantially perpendicular to a primary face of the third glass portion.