Colors

Left-clicking a color swatch brings up the color editing menu. This menu lists the site's current colors, recent colors you've used, and a slider which controls the opacity of the element.
Clicking More Colors brings you to the color selection menu. This menu contains a central shade selector and a hue selector to its right. Left-clicking the desired color will select it.
The color selection menu also lists R (red), G (green), and B (blue) values, and a hexadecimal (#) color value. The R, G, and B fields accept values between 0 and 255, where 0 is none of that color and 255 is all of that color, and the hexadecimal field accepts a six-digit hexadecimal color value where each digit is 0 through F (16).
The solid bar of color at the bottom of the color selection menu indicates which color is currently selected. Press the Done button to apply that color to the element.