function fade (color, opacity = 100) {
	const decimalFraction = opacity / 100;
	const hex = validateHex(color);

	// 1.
	const r = parseInt(hex.substring(0, 2), 16);
	const g = parseInt(hex.substring(2, 4), 16);
	const b = parseInt(hex.substring(4, 6), 16);

	// 2.
	const result = 'rgba('
		+ r + ','
		+ g + ','
		+ b + ','
		+ decimalFraction
		+ ')';

	return result;
}
Fade Color
	==============================

	Takes a hexidecimal color, converts it to RGB and applies an alpha value.

	@param {String} color
	@param {Number} opacity (0-100)

	1. convert hex to RGB
	2. combine and add alpha channel