This CSS Color Values Online Test helps you to Boost your Knowledge in PHP. CurrentColor keyword which is used in CSS color value online as a property that allows anyone to use the current value of the color without writing its actual value. The benefit is that you have to write the value once but you can use it multiple times. RGBA stands for Red-green-blue-alpha. In CSS color value online RGBA color values are an extension of RGB(it consists of the board of three colors red, green and blue) color values with an alpha channel which specifies the opacity of the color.