Using too many colors on web pages it's a bad practice. That's why SiteMan has its own idea about colors in the project. Each color of cell or template is a variable. For example, you have many templates each has many colored cells; you changed your mind and wanted to change one of the color. But that needs you to replace all values of that color, on each cell of each template. Too long. That's why we use variable colors. You can use them as many as you want and change later in one click.
If value you edit has color as value, in editable control (dropdown list) you can see all project colors. By choosing 'More colors' you can add a new color value to the project. It opens color picker where also you can see all project colors as custom colors.