What do the pink colors in Slic3r preview signify? If it signifies a problem, how do I fix it? What does the pink color in Slic3r preview mean? Yellow is my model, green is support, and pink is..?

If the pink color is some kind of warning, how do I fix it?
In slic3r preview, salmon (pink) represents infill, yellow represents perimeters, and green represents support material, including skirt and brim.