Each box contains a panel with a data attribute.
It contains a color code which will be used by a JavaScript which is included into this page.
Click in the content area of the boxes to set up a color.
Doubleclick to remove it.
<tc:box label="Green">
<tc:panel>
<tc:style customClass="demo-data-attribute"/>
<tc:dataAttribute name="color" value="#00ff00"/>
...