The phrase "little bronzer" refers to a small amount of a cosmetic product called bronzer, which is used to darken or give color to the skin. Full definition
«A little bronzer, a little lip, a little brow, a little mascara,» says Scott of her beauty choices at the gym. (health.com)
First off, you can use bronzer to create the illusion of thin legs; all you have to do is apply a little bronzer on your calves and thighs, and you've got skinnier - looking legs. (hintsandthings.com)