Light yellow tends to disappear into white, so it usually needs a dark color to highlight it. Shades of yellow are visually unappealing because they loose cheerfulness and become dingy. Dull (dingy) yellow represents caution, decay, sickness, and jealousy. Light yellow is associated with intellect, freshness, and joy.
The definition of a frown is a facial expression indicating displeasure by drawing the brows together and turning the lips downward. An example of frown is the face you make when you are unhappy about something.
If the smile and frown are stripped down to basics, a minimum number of muscles can be defined. A smile where only the corners of the lip and the upper lip are raised uses five muscle pairs; two of them raise the upper lip and three of them raise the corners.