You can choose a color via color box and slider, by typing the values in fields or using the mousewheel. Select brightness, hue, saturation, red, blue, green and opacity.
Press "To my colors" button to save the color and press a saved color to load it. Click it with right button to select the box without selecting the color.
You can copy the CSS-formated values from fields in the bottom. Click on the checkbox right to the fields to get the color in rgba or hsla format (with opacity).
In next versions there will be more functionality.
Script is taken from Colorpicker.com and edited.