Use active() to change the color of active selected choices. This utility
will only have an effect on elements with selectable choices, e.g.
checkbarInput().
active(tag, color)A tag element.
One of "red", "purple", "indigo", "blue", "cyan",
"teal", "green", "yellow", "amber", "orange", "grey", "white"
specifying the active color of selected choices.
Other design: affix,
background, border,
display, float,
font, height,
padding, scroll,
shadow, width