color
Color values are expressed in hexadecimal notation, including opacity (alpha) values. The order of expression is alpha, blue, green, red (aabbggrr). The range of values for any one color is 0 to 255 (00 to ff). For opacity, 00 is fully transparent and ff is fully opaque. For example, if you want to apply a blue color with 50 percent opacity to an overlay, you would specify the following: