Simplify the following text for a Grade 7 native English-speaking person.
Original: Cone cells , or cones , are photoreceptor cells in the retina of the eye that are responsible for color vision ; they function best in relatively bright light , as opposed to rod cells that work better in dim light .
Simplified: Cone cells or simply cones special photoreceptor cells in the retina . They react to light and work best in relatively bright light .