Here are some salient features.

1. There are three sliders, one for red, one for green, one for blue.
2. The sliders have a range from 0 to 255 and start at 255.
3. Moving the sliders causes the color in the box to change and the hex code displayed to change.
4. display:inline-block is your friend!
5. The box starts off being white.
6. The hex code is initially FFFFFF.