Small Developer Tools UI question: where is the color picker?

Things I have tried

I was playing with changing element colors in the UI and was happy to see a color picker included when dealing with color values. However, for some color: attributes there is a picker in the GUI, and for some there is not. See this picture:

What I’m trying to do

I’m just curious, why does the first color: not get a picker and the second color: get a picker? And how do I add a picker to a non-picker value? I want to dial it in and a picker is so helpful for that.