Theme::prepareColor

static function prepareColor(string $color): string
{
	$color = HtmlFilter::encode(trim($color));

	if($color[0] !== '#')
	{
		$color = '#' . $color;
	}
	if(!self::isHex($color))
	{
		return self::DEFAULT_COLOR;
	}
	if(mb_strlen($color) === 4)
	{
		$color = $color[0] . $color[1] . $color[1] . $color[2] . $color[2] . $color[3] . $color[3];
	}

	return $color;
}