Made the non-spotlighted stuff a little darker.
Explicitly set the background-color and text color in the body and tick text.
Use transitions in layer's click handler to change colors, and change the body color, text color, and tick color as well to darken everything. Do the same in reverse when a non-cell is clicked.
Put spotlight-clearing in its own function, and called it when a spotlighted layer is clicked a second time. Also, bound it to the 'html' element's click event so that clicks anywhere but the graph turn the lights back on.